RME Audio ADI-2 DAC User manual

User’s Guide
ADI-2 DAC FS
Sonus Verus
2 Channel Digital / Analog Converter
SPDIF (AES/ADAT) Interface
32 Bit / 768 kHz Digital Audio
USB 2.0 Class Compliant
Extreme Power Headphone Output
Super Low Noise IEM Output
Digital Signal Processing
Advanced Feature Set
Remote Control
32 Bit / 768 kHz
Hi-Res Audio
SteadyClock™ FS SyncCheck™

2 User’s Guide ADI-2 DAC © RME
General
1 Introduction ...............................................................5
2 Package Contents .....................................................5
3 System Requirements ..............................................5
4 Brief Description and Characteristics.....................6
5 First Usage - Quick Start
5.1 Connectors and Controls ........................................7
5.2 Quick Start ..............................................................7
5.3 Operation at the unit................................................8
5.4 Overview Menu Structure .......................................9
5.5 Playback................................................................10
5.6 Digital Recording...................................................10
6 Power Supply...........................................................11
7 Firmware Update.....................................................11
8 Features Explained
8.1 Extreme Power Headphone Output......................12
8.2 IEM Headphone Output ........................................13
8.3 5-band Parametric EQ ..........................................13
8.4 Bass / Treble .........................................................14
8.5 Loudness...............................................................14
8.6 Crossfeed..............................................................15
8.7 DSP Limitations.....................................................16
Operation, Controls and Display
9 Operation and Usage ..............................................18
10 Front Panel Controls
10.1 Keys .....................................................................18
10.2 Encoders ..............................................................18
10.3 Remote.................................................................19
11 VOL ...........................................................................19
12 I/O..............................................................................19
12.1 Subpage Settings.................................................19
12.2 Subpage Parametric EQ ......................................20
12.3 Subpage Bass / Treble ........................................21
12.4 Subpage Loudness ..............................................22
13 EQ .............................................................................23
14 SETUP
14.1 Options
14.1.1 Hardware/Diagnosis.....................................25
14.1.2 Clock ............................................................26
14.1.3 Device Mode ................................................26
14.2 Load/Store all Settings.........................................27
15 Meter Screens
15.1 Dark Volume ........................................................27
15.2 Analyzer ...............................................................28
15.3 State Overview.....................................................28
16 Warning Messages..................................................30
17 DSD Operation
17.1 General ................................................................31
17.2 Direct DSD ...........................................................31
17.3 DSD Playback ......................................................32
17.4 DSD Record .........................................................32

User’s Guide ADI-2 DAC © RME 3
Inputs and Outputs
18 Digital Inputs ........................................................... 34
19 Analog Outputs
19.1 General ................................................................34
19.2 Line Out RCA....................................................... 34
19.3 Line Out XLR ....................................................... 35
19.4 Phones Out.......................................................... 35
19.5 IEM Out................................................................ 36
19.6 Using more than one Output................................ 36
Installation and Operation - Windows
20 Driver Installation....................................................38
21 Configuring the ADI-2 DAC
21.1 Settings Dialog..................................................... 39
21.2 Clock Modes - Synchronization ........................... 40
22 Operation and Usage
22.1 Playback .............................................................. 40
22.2 Multi-client Operation........................................... 40
22.3 Multi-interface Operation ..................................... 41
22.4 ASIO ....................................................................41
23 DIGICheck Windows............................................... 41
Installation and Operation – Mac OS X
24 General..................................................................... 44
24.1 Configuring the ADI-2 DAC.................................. 44
24.2 Clock Modes - Synchronization ........................... 44
24.3 Multi-interface Operation ..................................... 45
25 DIGICheck Mac........................................................ 45
Installation and Operation – iOS
26 General..................................................................... 48
27 System Requirements ............................................ 48
28 Setup ........................................................................ 48
29 Supported Inputs and Outputs.............................. 48

4 User’s Guide ADI-2 DAC © RME
Technical Reference
30 Technical Specifications
30.1 Digital Inputs ........................................................50
30.2 Analog Outputs ....................................................50
30.3 Digital ...................................................................51
30.4 General ................................................................51
30.5 Connector Pinouts................................................51
31 Technical Background
31.1 Lock and SyncCheck ...........................................52
31.2 Emphasis .............................................................53
31.3 SteadyClock FS ...................................................53
31.4 Filter Curves 44.1 kHz .........................................54
31.5 Frequency Response...........................................54
31.6 DA Impulse Responses .......................................55
31.7 Total Harmonic Distortion Measurements ...........56
31.8 Loudness..............................................................56
31.9 Extreme Power Charts.........................................57
31.10 Phones Distortion Comparison ............................58
31.11 Impedance based Level Meters (Phones) ...........58
31.12 USB Audio (Windows) .........................................59
31.13 Operation in the Hi-Fi Environment......................60
31.14 Digital Volume Control .........................................61
31.15 Bit Test .................................................................63
31.16 Block Diagram......................................................64
Miscellaneous
32 Accessories .............................................................66
33 Warranty...................................................................66
34 Appendix ..................................................................67
35 Declaration of Conformity ......................................68

User’s Guide ADI-2 DAC © RME 5
1. Introduction
RME’s ADI-2 DAC is a true milestone in many ways. Looking at the multitude of DA converters,
USB DACs and dedicated headphone amps available, RME developers felt they all lacked ob-
vious features that are unavoidable to enjoy operation as well as when listening to music. And
while many of those devices claim to use the latest state-of–the–art whatsoever converter chip,
serious magazines and RME staff were repeatedly disappointed to find that in the end the stel-
lar technical data published in ads and datasheets were nowhere to be found.
With the ever growing popularity of headphones and latest DA chips pushing technical data
further, the time was right for a new RME gem. A unit with specs that are as real as RME‘s
reputation, a feature set that is unheard of, useful features that for unknown reasons no one
else implemented, and two extremely powerful headphone outputs, that will be your new refer-
ence in accuracy and dynamic range.
Here it is – the ADI-2 DAC:
x A high-end DA converter in professional studio quality
x A headphone amplifier in true high-end quality
x A USB DAC like no other - the most versatile and capable one around
x A high-end DAC frontend and headphone amp for iPad and iPhone
x An SPDIF/ADAT playback system
x A DSD playback solution
2. Package Contents
x ADI-2 DAC
x Remote control with battery
x Manual
x External switched power supply, lockable connector, DC 12 V 24 W
x Power cord
x USB cable, 1.8 m (6 ft)
3. System Requirements
General:
x Power supply 12V DC, 1.0 A or up
For computer based operation:
x Windows 7 or up, Intel Mac OS X (10.6 or up)
x 1 USB 2.0 port or USB 3 port
x Computer with at least Intel Core i3 CPU
For iOS based operation:
x iPhone or iPad with iOS 7 or up
x Dock or Lightning to USB adapter

6 User’s Guide ADI-2 DAC © RME
4. Brief Description and Characteristics
The ADI-2 DAC is a 2-channel digital to analog converter in a half-rack (9.5") enclosure of 1 U
height. Latest 32 bit / 768 kHz converters offer up to 120 dBA signal to noise ratio. This value is
not only printed in the brochure – it is what the unit achieves in real-world operation.
Reference class tech specs throughout are combined with an unprecedented feature set. A
powerful DSP adds all kinds of useful audio processing, including 5-band parametric EQ, fast
Bass/Treble adjustment, Crossfeed, and a new concept in Loudness sound control.
Operation is quick and easy through 3 encoders with push button function and 4 more buttons
to access dedicated menus. The unit remembers all current settings, even the menu position.
Additionally the unit’s whole setup as well as equalizer settings can be stored under individual
names.
A high resolution IPS panel for the graphical operation surface eases operation even more, and
displays further functions provided by the DSP, namely Peak level meters, a 30-band analyzer
in DIGICheck biquad filter technology, and a State Overview screen listing the current states of
SPDIF, USB and clock.
The digital inputs SPDIF coaxial and optical can be used alternately. SPDIF optical also sup-
ports 2 channels of ADAT operation, at up to 192 kHz.
When used as USB interface, Class Compliant UAC 2 enables up to 768 kHz sample rate on an
iPad. The same is available on computers for high resolution of PCM, DXD and DSD at up to
768 kHz / DSD256.
The balanced and unbalanced outputs are fitted with both XLR and RCA jacks. The unit uses a
fully balanced and DC-coupled circuit design, for highest phase accuracy at lowest roll-off.
The Extreme Power headphone output provides reference sound and headroom. RME’s unique
IEM output offers unprecedented low noise for latest super-sensitive In-Ear phones.
To maintain the full dynamic range within the best operating level, discrete 4-stage reference
level settings were realized for maximum dynamic range (-5, +1, +7, +13 dBu). The digital vol-
ume control of the ADI-2 DAC operates distortion free over a range of 190 dB, therefore does
not cause any tampering of the sound.
The ADI-2 DAC supports all sample rates between 32 kHz and 768 kHz. Furthermore, RME's
SteadyClock FS guarantees exceptional performance in all clock modes. Thanks to a highly
efficient jitter suppression, the DA-conversion always operates on highest sonic level, being
completely independent from the quality of the incoming clock signal.
The ADI-2 DAC shines in both studio and home usage. Its click- and noise-free on/off operation
and a comfortable, illuminated standby button add to the soft, modern desktop design. An Auto-
Dark mode removes all disturbing lights without sacrificing operation and setup. The included
remote control offers comfortable control of the ADI-2 DAC directly from the preferred listening
position with stellar flexibility through four additional, freely programmable keys.
Battery operated usage is possible through a 12V connector.

User’s Guide ADI-2 DAC © RME 7
!
5. First Usage – Quick Start
5.1 Connectors and Controls
The front of the ADI-2 DAC has 3 hi-precision rotary encoders with push function, 4 buttons, a
standby power button, a high resolution IPS display, and two TRS headphone outputs.
The output channels Phones and IEM feed two phones outputs via two independent driver cir-
cuits, optimized for both high and low impedance headphones. Their unbalanced output signal
is of highest quality. With up to 120 dBA Dynamic Range there exists no audible hum and noise
at those outputs.
In case a phones output is to be used as line output, an adapter TRS plug to RCA phono plugs,
or TRS plug to two TS plugs is required.
The rear of the ADI-2 DAC has 2 RCA sockets as unbalanced outputs and 2 XLR sockets as
balanced outputs, TOSLINK optical/coaxial input, a USB socket, and a lockable power socket.
The short circuit protected, low impedance XLR line outputs do not operate servo bal-
anced! When connecting unbalanced equipment via XLR, make sure pin 3 of the XLR
output is not connected. A connection to ground might cause a decreased THD (higher
distortion) and increased power consumption!
Optical In (TOSLINK): The unit automatically detects SPDIF or ADAT input signals. Note that
only channels 1/2 from the ADAT stream can be accessed. SMUX and SMUX4 (up to 192 kHz)
are still supported.
USB 2.0: Standard USB socket for connection to the computer. The ADI-2 DAC operates as
Class Compliant device, in 2-channel mode. It can be directly used with Mac OS X and iOS
(iPad, iPhone). For Windows the RME MADIface series driver adds WDM and ASIO.
Socket for power connection. This socket supports locking type jacks as found on the included
RME DC power supply. After inserting the connector carefully turn it by 90° so that it locks.
5.2 Quick Start
Connect the unit to the included power supply and push the red lit Standby button to start. The
ADI-2 DAC ships with Source Auto (I/O – Line Out – Settings - Source) as default setting.
Remove the transparent plastic isolator by tearing it out of the remote control bottom. Then use
the remote to switch to the desired input signal, USB, SPDIF optical or SPDIF coaxial.
Factory default for remote buttons 1 to 4:
1: Mono, 2: Loudness, 3: B/T Enable, 4: Dim
The ADI-2 DAC is a 2-channel I/O interface when connected via USB. Under Windows install
the RME WDM/ASIO driver to play back a stereo signal from the computer.
When not connected to USB the ADI-2 DAC will work as SPDIF to analog converter. In mode
Source Auto the input is switched to SPDIF automatically as soon as USB is no longer de-
tected.
The unit remembers all settings, and loads these automatically when it is switched on again. To
switch off, press the Standby button for at least 0.5 seconds.

8 User’s Guide ADI-2 DAC © RME
5.3. Operation at the Unit
Useful information for a smooth start:
Turning the big VOLUME knob brings up the Volume screen
of the currently active output. The status bar at the bottom of
the display shows the current volume settings' dB value.
The header shows the currently selected output, the
hardware reference level and Auto Ref Level mode if
activated (Ref Lev, see chapter 12.2.1).
The EQ is set up either directly within the I/O menu structure (key I/O, turn encoder 2 to access
Settings, Parametric EQ, Bass/Treble and Loudness), or via the graphical EQ screen which is
shown after pressing the EQ key. In this screen the cursor has three positions: top, the EQ pa-
rameter line below the Bode plot (frequency response curve), and the filter selection type for
band 1 and 5 (Peak, Shelf, Low/High Cut). The cursor is moved up or down by pushing encoder
1 or 2 repeatedly.
With the cursor in the top position only the current band is
highlighted (B1…). Turning VOLUME changes the band's
gain, pushing it changes to the next band. Switching
between the bands can also be done by turning encoder 2.
When in the EQ parameter line, all values are no longer
grayed out. In this state the big encoder steers Gain,
encoder 1 Frequency, and encoder 2 Quality factor. This
way the EQ is extremely fast set up and edited.
The graph has 5 different colors matching the 5 bands that can be adjusted. If the line is just
grey the EQ is disabled (bypass). The EQ can be enabled in the second menu which comes up
by pushing the EQ key a second time.
The unit offers three informative screens on the top level: Analyzer, State Overview and Dark
Volume. Change between them by pushing encoder 1 or 2 whenever any of them is displayed.
To quickly call them up simply press any of the four function keys several times.
In all these top level screens turning encoder 1 and 2 brings up the quick access to Bass and
Treble, with ± 6 dB maximum boost/cut.
The included remote control uses a standard lithium battery CR2025. The remote allows to turn
the ADI-2 DAC on and off (standby), to change the volume, to mute the output and to select the
playback source (SPDIF, optical, USB). Additionally it has four freely programmable keys, that
can be assigned to 19 different commands/actions (see chapter 14.1.1).

User’s Guide ADI-2 DAC © RME 9
5.4. Overview Menu Structure

10 User’s Guide ADI-2 DAC © RME
5.5 Playback
In the audio application being used, the ADI-2 DAC must be selected as output device. It can
often be found in the Options, Preferences or Settings menus, as Playback Device, Audio De-
vices, Audio etc. After selecting a device, audio data is sent to the ADI-2 DAC and available at
its analog outputs.
Increasing the number and/or size of audio buffers and/or buffer size may prevent the audio
signal from breaking up or having drop outs.
5.6 Digital Recording
In digital audio, it is mandatory for a unit like the ADI-2 DAC to be in total sync to the external
digital device, as so called clock slave. Taking this into account, RME added a comprehensive
I/O signal status display to the ADI-2 DAC, showing sample frequency, lock and sync status in
the State Overview screen and the bottom status bar.
The sample frequency shown in the State Overview screen is useful as a quick display of the
current configuration of the unit and the connected external equipment. If no sample frequency
is recognized, it will show - - (No Lock).
This way, configuring any suitable audio application for digital recording is simple. After con-
necting it the ADI-2 DAC displays the internal and external sample rate. This parameter can
then be changed in the application’s audio attributes (or similar) dialog.
To enable the recording of the SPDIF input via USB go to I/O, Source, and select either USB
(Rec opt.) or USB (Rec coax). Record SPDIF optical and Record SPDIF coaxial activate the full
duplex operation with USB: The respective SPDIF signal is clock source and can be recorded
via USB. The analog output signal is now the current USB playback, no longer the SPDIF input
signal. For this to work the USB playback sample rate must be identical to the SPDIF input sig-
nal.
6. Power Supply
In order to make operating the ADI-2 DAC as flexible as possible, the unit has a universal DC
input socket, accepting voltages from 9.5 Volts up to 15 Volts. An internal switching regulator of
the latest technology with high efficiency (> 90%) prevents internal hum noise by operating
above audible frequencies. Internally the switching regulator is followed by standard linear regu-
lators, followed by super low-noise linear regulators. Therefore the ADI-2 DAC achieves its
technical specs even with less optimal power supplies. Or in other words: the choice of power
supply is not critical.
Still the unit includes a high-quality switching power supply, 12 V / 2 A, which not only accepts
any mains voltage between 100 V and 240 V (usable world-wide), but is also fully regulated
against voltage fluctuations and suppresses line noise. Additionally it only weights 150 g in spite
of its high power of 24 Watts.
The DC input of the ADI-2 DAC also allows for the use of a rechargeable lead-battery or LiPo
instead of a power supply, for completely independent mobile operation and ground isolation. A
matching connection cable (power jack to terminals 6.3 mm) is available from RME. Special
power banks in the range of 10,000 mAh and up can be found equipped with a 12 V output.
These offer a perfect solution for mobility as well as ground isolated operation, for small money.

User’s Guide ADI-2 DAC © RME 11
7. Firmware Update
The ADI-2 DAC might receive improved features or bug fixes by a firmware update. This update
will be available from the RME website, section Downloads, USB. Download the tool that
matches your operating system (Mac or Windows), then unpack the zipped archive.
The Flash Update Tool updates the firmware of the ADI-2 DAC to the latest version. Under
Windows it requires an already installed MADIface series driver, which is found on the same
download page.
Start the Flash Update Tool. It displays
the current revision of the ADI-2 DAC
firmware, and whether it needs an
update or not. If so, then simply press
the 'Update' button. A progress bar will
indicate when the flash process is
finished (Verify Ok).
After the update the ADI-2 DAC needs
to be reset. Push the standby button to
switch it off for 5 seconds.
When the update unexpectedly fails
(status: failure), the unit's Safety BIOS
will be used from the next boot on, the
unit stays fully functional. The flash
process should then be tried again.
The flash process does not affect user
data like sample rate choices, EQ
settings or Setups.
Returning to Factory State
In case a total reset is desired: hold encoder 1 and the VOL key pushed while turning on the
unit. This will reset all memory to factory default. Setups and EQ Presets stored by the user will
not be deleted.
Another way to reset the unit is by selecting the Factory Setup in the Setups section and load-
ing it.

12 User’s Guide ADI-2 DAC © RME
8. Features Explained
8.1 Extreme Power Headphone Outputs
During the development of the ADI-2 Pro an extensive research on today’s headphone amp
technology as well as headphones has been carried out. Many (many!) headphones later a
maximum output level of +22 dBu (10 Volt) was set as development goal, as it will drive even
insensitive headphones sufficiently, while a maximum output current of around 260 mA per
channel will result in lots of power for lower impedance phones (1.5 Watts @ 32 Ohm).
Limiting the current makes a lot of sense. It is needed to control the internal power supply, to
not fully overdrive (and destroy) weaker headphones, and prevents malfunction at short-circuit
state. The Extreme Power output stage acts like a small power amplifier, so it got a similar fea-
ture set: a relay that mutes and interrupts the connection to the phones, a DC sensing circuit to
prevent DC at the output (DC destroys your precious phones already when the rated watts are
not even closely reached!), and an over-current protection circuit that will notice when a short-
circuit causes too high current, preventing the output stage to get destroyed. In light of the mali-
cious treatment of this output stage during development it needs to be mentioned that it can not
be destroyed by a short-circuit at the output nor by overheating. Still some extra safety won’t
hurt, and the over-current protection circuit got in.
A goal during development was to build a headphone amp that not only reaches very low THD
un-loaded (the typical way of measuring it), but very low THD values with a 32 or 16 ohm real-
world load. This was achieved in the new Extreme Power headphone driver output stage. It
uses 6-fold spread power technology, improved thermal conductivity and a special super-low
distortion driver design. The result is THD below -110 dB at 32 Ohm load even near full output
level (clipping), the same SNR as the DAC provides (120 dBA), an output impedance of only
0.1 Ohms, totally stable operation, and a frequency response from 0 Hz up to 80 kHz, with just
0.5 dB decrease at the top end. The result: No audible hum, noise or distortion, fully transparent
and crystal clear sound at any volume setting, for any personal taste in any application.
And there is more. The headphone sockets of the ADI-2 DAC have sensor contacts. The unit
always knows when a headphone jack is inserted or removed. The DSP uses this information
for several superior, partly never-seen before features. For example the ADI-2 DAC activates
the mute relay half a second after the phones plug has been plugged in, then the DSP ramps
up the volume slowly from lower level to the last used state. Comfortable? Luxurious? Yes, but
the main reason for it was to give the user a chance to react. Extreme Power headphone out-
puts set to full output level, music already playing at full level, inserting the phones, and the
moment the relay switches on the doctor is called, diagnosing sudden deafness - this should
and can not happen with the ADI-2 DAC. When the volume is ramped up one has the time to
either quickly set the phones off, unplug the phones again, or to grab the Volume knob to
quickly turn it down.
To guarantee that the Volume knob will be set to control the correct outputs in that moment, the
DSP also sets the Volume knob automatically to the output where phones had been plugged in.
And even returns the setting when the phones are unplugged again.
This is just an example of how intelligent and elaborate the control logic of the ADI-2 DAC has
been implemented. There are lots of such functions and features that might even stay un-
noticed, making the unit behave fail-proof as well as easy to operate.
But isn’t +22 dBu, or Hi-Power as it is called in the menu, much too loud for modern phones?
That depends. There are still phones that need higher levels. Music can be low in volume but
consume a lot of power, especially with lots of sub-bass. And lots of headroom is always nice to
have. Typically with Hi-Power off, which equals +7 dBu maximum output level, modern music
and modern headphones, Hi-Power is mostly not needed. But you will notice that even with Hi-
Power active, which requires to use a volume setting 15 dB lower as usual, the sound stays the
same, and there is no audible noise or hum at the phones output (provided the source is clean,
of course). So even at a Volume setting of -40 dB the ADI-2 DAC delivers perfect sound quality,
being a no-brainer in daily use as how to set it.

User’s Guide ADI-2 DAC © RME 13
8.2 IEM Phones Output
In Low Power mode, the Extreme Power design of the ADI-2 DAC turns it into one of the world's
lowest noise headphone outputs. However, a few IEMs are so incredibly sensitive (means loud)
that, despite all the technical super specs, a faint noise could become audible (current example:
Campfire Andromeda, at least 20 dB louder as modern, already as loud categorized head-
phones).
The usual remedy is the use of an external, passive voltage divider 16 Ohm to 1 Ohm, either
self-built, or bought as a pre-made product.
Since IEMs are not only increasingly popular, but are generally more sensitive than normal
headphones, and a powerful Extreme Power output stage always entails the risk of destruction
of the IEM with wrong settings, the ADI-2 DAC has been equipped with an additional output
stage optimized for IEMs. Here, there is no Extreme Power, but extreme noise freedom, with
the same sensational low distortion as at the big phones output, but a maximum output level of
only -3 dBu. For most users this will suffice even for ordinary headphones, in particular portable
ones with the mini TRS connector. This output with < 0.1 Ohms impedance turns the ADI-2
DAC into a reference for all types of headphones, from over-ear planar up to in-ear multi-
drivers.
8.3 5-band Parametric EQ (PEQ)
While no equalization as well as listening only straight linear has been a mantra for many years,
research has proven that no ears are identical, and that especially in near-field listening (with
phones) the biological differences alone make individual equalization mandatory. No two pairs
of ears hear the same thing, that’s a fact. Additionally personal taste makes people like different
sound signatures, which can easily be copied or made more similar (equalized…) on different
headphones using a good EQ. The advantages of using an EQ outweigh any alleged disadvan-
tages - which so often turn out to be wrong at closer inspection.
Having used PEQ to linearize as well as to better meet personal taste with a variety of head-
phones, RME found 5 bands of parametric EQ to be the best balance between occupied DSP
resources and efficient sound treatment. While it is true that on some phones rebuilding an ex-
act response curve needs more than 5 bands, one quickly realizes that very narrow peaks and
notches make no audible difference when compensating them. Their acoustical energy is too
low to get audible. Ignoring those narrow peaks/notches and only taking care of deviations that
require a quality factor of 3 or below, the 5 band parametric EQ turns into a very efficient tool
even for problematic phones.
This is one of the many major features that can’t be found on any similar device: a high-quality
5-band parametric EQ, usable at up to 768 kHz sample rate, easy to set up and adjust, with a
graphical display showing the resulting curve, and multiple storage places including individual
naming. So whatever EQ setting you need, it is loaded and modified quickly. And to make this
feature really useful the DAC offers three individual EQ settings - one each for rear out, Phones
and IEM.
On a related topic: These days many people suffer from hearing loss in varying degrees. No
matter if it is biological, from abuse or an accident - hearing impaired is a plague of modern
times. And – no surprise when thinking about it – it never affects both ears identically. The
number of people having one sided hearing problems is huge, but they have learned to live with
an industry that totally ignores them. Although the solution is as simple as logical – have the EQ
be adjustable independently for left and right. Basically digital EQs are calculated this way, the
common controls are just for making it easier to operate. The ADI-2 DAC includes an option
called Dual EQ – a heaven send feature for many, for sure.
Of course a 5-band parametric EQ is also suitable for speaker and room correction, another
application where separate EQ left/right setups are necessary. Using the ADI-2 DAC as DAC
for the main monitors will benefit from this and all the other typical RME features available on all
analog I/Os: Phase and Mono in various options, Width and M/S Processing.

14 User’s Guide ADI-2 DAC © RME
8.4 Bass / Treble
The simpler form of EQ has been the Bass and Treble controls as they are found on any ‘stan-
dard’ HiFi stereo amplifier. They easily and quickly allow to modify the sound to your personal
liking (more or less Bass, more or less Treble, obviously). An even more useful application is to
quickly change the amount of Bass / Treble in smaller quantities so that music compilations
don’t have one song making the cones fall out while another one makes you think that really
happened. Producers and mastering engineers not only have their own taste, they also some-
times fail in providing a mix that is on an average sound level compared to others. In that mo-
ment a quick turn on the two ADI-2 DAC’s small encoders will make the music sound perfect.
These Bass and Treble controls are limited to ± 6 dB. Everything exceeding such values should
be handled by the EQ, and/or calls for better speakers/phones. The corner frequency and qual-
ity factor of Bass and Treble is user-adjustable in the display’s menu, making this feature even
more useful. Adapt it to meet your speakers/phones or your personal taste – it will greatly im-
prove your pleasure in listening to music again.
8.5 Loudness
Another legacy of HiFi amplifiers: there has not been a single one missing a feature called
Loudness. It tries to address the changes in frequency-dependent hearing sensitivity over dif-
ferent volume levels. If one listens to music loud, then drops the level by at least 20 dB, sound
loses punch and glitter. HiFi amps tried to fight this effect by adding more bass and treble the
lower the volume was set. Unfortunately that never worked as intended, and just became an
additional bass/treble booster. Reason: the manufacturer of the HiFi amp could not know what
volume any position of the volume knob equals at the customer’s home. Room size, room
dampening and efficiency of the used speakers are all unknown.
But the effect of loss in perceived sound exists (read about the Fletcher-Munson curves), and
can be easily reproduced with any serious gear by comparing normal volume and DIM state
(usually -20 dB). The ADI-2 DAC offers Loudness for the analog stereo outputs, and probably is
the first time that Loudness works as intended. The user can decide how much maximum gain
in Bass and Treble should occur at lower volume settings. The user also sets the Low Vol Ref-
erence, where maximum gain is achieved. After extensive tests a 20 dB range has been de-
fined as range for maximum gain to no gain while increasing volume. That seemed to be the
perfect definition of the range that needs to be addressed by Loudness.
Here is an example on how it works: the user’s typical lowest level listening volume is at -35 dB
at the unit. This value is now set by the user as Low Vol Ref in the Loudness menu. Then Bass
and Treble Gain can be set between 0 and +10 dB. Default is +7 dB for both. Increasing the
volume by turning the Volume knob causes the gain in Bass and Treble to be lowered smoothly
over a range of 20 dB. So when Volume is set to -15 dB, the music is not only quite loud, but
Loudness’ Bass and Treble are then at 0 dB gain. See chapter 31.8 for graphs.
No matter how sensitive the connected phones or speakers are, no matter how much increase
in Bass and Treble are desired – with the ADI-2 DAC one can finally adjust it to meet the per-
sonal hearing and taste. Loudness finally works as it should have worked from the start - an-
other unique feature in the ADI-2 DAC.
Note: Loudness works best in Auto Ref Level mode due to the seamless dBr scale of the vol-
ume control. Without Auto Ref Level active, manually changing the Ref Level will change the
volume without changing the VOLume value (dB). As Loudness is referenced to a 'Low Vol Ref'
setting it then might no longer work as intended, and needs the Low Vol Ref value to be ad-
justed.

User’s Guide ADI-2 DAC © RME 15
8.6 Crossfeed
While headphones open the sound stage and make everything easier to hear and to locate by
spreading the narrow sound field of stereo speakers to the left/right extreme, some people
would like to have a listening situation that is more comparable to a standard speaker setup.
The ADI-2 DAC includes Crossfeed to address this wish. Crossfeed reduces the artificial sur-
round ambience that some productions have to make them sound better on speakers, but which
sounds unnatural on a headphone.
The Bauer Binaural method is used, with five selectable strengths of narrowing the upper fre-
quencies. This advanced method, which also includes a small delay and correction of the fre-
quency response, works quite well, and is another useful addition as well as a unique feature on
a device like the ADI-2 DAC.
Details on internal settings
The Crossfeed effect is mainly defined by the filter frequency and the amount of crossfeed, here
given as damping factor:
1: 650 Hz, -13 dB (just a touch)
2: 650 Hz, -9.5 dB (Jan Meier emulation)
3: 700 Hz, -6 dB (Chu Moy emulation)
4: 700 Hz, -4.5 dB (30° 3 meter emulation)
5: 700 Hz, -3 dB (example how even stronger would sound)

16 User’s Guide ADI-2 DAC © RME
8.7. DSP Limitations
There is never enough DSP power – no matter how much you add (frustrated developer).
That is true even for the ADI-2 DAC. Although being equipped with a quite capable 2.17 Giga
FLOPS DSP chip, plus using the FPGA to perform further calculations (RME’s virtual DSP for
mixing/routing, level meters, filtering, Crossfeed), 768 kHz sample rate takes its toll. The calcu-
lation power available at 48 kHz is divided by 16 (!) then. Even at 384 kHz it is just 1/8 of that at
48 kHz. The DSP in the ADI- 2 Pro performs:
Bass/Treble and Loudness for 2 channels
5-band parametric EQ for 2 channels
Standard phase functions for 2 channels
Crossfeed for 2 channels
30-Band bi-quad bandpass filter spectral analyzer
Peak Level meters for all channels
Display rendering
Volume control on 2 channels
Several controller-like functions, like volume ramp-up, mute, signal routing control etc.
DSD to PCM conversion (for level meters)
At 48 kHz that is no big deal, at 192 kHz it already needs efficient coding and a better DSP chip.
But at 768 kHz you need a DSP with 4 times the power of the ‘better’ one. Therefore there is no
way around disabling some functions at higher sample rates. Fortunately those limitations have
only small impact in real-world usage:
x At sample rates 705.6 kHz and up Crossfeed or EQ can be active, not both at the same
time. Bass/Treble and Loudness are not available.
The high sample rates available in the ADI-2 DAC also exceed the capabilites of the digital in-
put. Both AES and SPDIF are limited to 192 kHz, and there is no way around it. Therefore all
higher sample rates are only usable analog and with USB. And in iOS mode when using an
iPad/iPhone with an app that supports such high sample rates (Neutron, Onkyo HF-Player etc.).
DSD comes with its own limitations. DSD is a 1 bit stream of data that can not be processed
digitally. There is no Bass, Treble, Loudness, EQ etc. possible at all. The volume control is no
longer done by the DSP, but the DAC chip, which converts DSD into PCM to be able to offer
level (volume) modification. You won’t notice that, volume operation at the ADI-2 DAC is seam-
less and behaves identical in any mode. The DSP now performs an additional DSD to PCM
conversion, to be able to show the audio signal on the level meters and the Analyzer – a unique
feature of the ADI-2 DAC.
Even more extreme is DSD Direct. If activated (SETUP, Options, Device Mode), the DSD sig-
nal is not converted to PCM within the DAC, therefore there is no volume control at all – except
for the analog reference levels, which can be used to set the coarse output level/volume. Left
with no volume control, the ADI-2 DAC intentionally deactivates the headphone outputs in DSD
Direct mode – the analog signal is only available at the rear outputs.

User’s Guide ADI-2 DAC © RME 17
User’s Guide
ADI-2 DAC
Operation, Controls and Display

18 User’s Guide ADI-2 DAC © RME
9. Operation and Usage
General operation and usage of the ADI-2 DAC are explained in chapter 5.2, Quick Start, and
chapter 5.3, Operation at the unit.
The ADI-2 DAC ships with Source: Auto active.
State Overview is especially useful to check the state of digital input signals as well as the cur-
rent settings with USB. It also displays several warning messages which might explain why
currently no sound is audible. See chapter 15.3 for details.
The following chapters explain all the controls and menu items in detail.
10. Front Panel Controls
10.1 Keys
The four back-lit function keys offer quick access of important parameters within the menu
structure. After pressing one of the four keys the corresponding menu is shown in the display.
The unit remembers the last selection per key, so re-visiting a formerly changed parameter is
easy. To leave the menu push the same key a second time, or any other key two times. The
display will revert to the top screen that was active before entering the menu.
10.2 Encoders
The encoders can be turned endlessly, but also pressed, adding a push button function. The
current functionality of all encoders is shown in the display. The big Volume knob usually con-
trols volume for all outputs.
Turning the small encoders 1 and 2 either changes the current parameter, or moves the selec-
tion/cursor horizontally to the next page. Pressing the encoders 1 and 2 moves the selec-
tion/cursor vertically, up with 1 and down with 2, as indicated by the arrows in the display.
Example: Press the key SETUP. The menu Setups is now
shown. 1 within the circle on the right side indicates that by
turning encoder 1 more pages are available. Turn encoder 1
left to enter Options. Now turn encoder 2 to scroll
horizontally through all the subpages offered under Options:
Hardware/Diagnosis, Device Mode, Clock. By pressing
encoder 2 the cursor moves down, by pressing encoder 1
back up. On a selected field or entry, 2 to the right indicates
that the current parameter can be changed by turning
encoder 2.

User’s Guide ADI-2 DAC © RME 19
10.3 Remote Control
The included remote control allows to turn the ADI-2 DAC on and off
(standby on/off)), to change the volume (Volume +/-), to mute the output
(speaker off) and to select the playback source (SPDIF coaxial, optical,
USB).
Additionally it has four freely programmable keys that can be assigned to
21 different commands/actions (see chapter 14.1.1). Commands like
mono, EQ on/off, Loudness on/off or polarity can be issued live and in
real-time from the preferred listening position.
The remote requires a standard lithium battery CR2025 (included). For
first time usage please tear out the transparent plastic isolation
completely.
11. VOL
The VOL key brings up an extended volume screen with balance control. Volume can then be
adjusted by both Volume knob and encoder 1. Encoder 2 sets the Balance parameter.
The volume and balance setting is also found in the menu
I/O - Settings, at the end of the list.
The status bar at the bottom of the display shows the
volume setting's current dB value.
A push on encoder 1 (B) mutes the current output. The text
in the blue field shows Line Out - muted. A second push
exits the mute state.
Pushing the VOL key again reverts to the level meter screen that has been active before.
Line Out defaults to Auto Ref Level enabled. The current volume setting is then shown as dBr
(dB relative), and the unit automatically switches to the matching hardware reference level to
optimize the dynamic range.
12. I/O
The I/O menu has all the settings for the three analog outputs: Line Output, Phones and IEM.
Source defines which signal is fed to the analog outputs – USB, SPDIF optical or SPDIF coax-
ial. The submenu Parametric EQ mirrors the settings done in the graphical EQ screen.
The ADI-2 DAC processes all audio in the digital domain. Having only one stereo digital to ana-
log converter, different settings of volume, equalizer or effects for the three outputs is not possi-
ble when used simultaneously (the ADI-2 Pro has two DACs, therefore can process two stereo
signals independently with different settings).
But typical operation is alternate usage of the outputs – rear Line Out or Phones or IEM. The
ADI-2 DAC treats all outputs separately, and stores a complete set of parameters for each (ex-
cept the synchronized Source selection). Depending on the used output, detected by the sensor
contacts in the output jacks, the respective settings are loaded automatically, and this way the
formerly used volume, EQ and much more. In alternate usage the unit thus provides three fully
independently to configure outputs.

20 User’s Guide ADI-2 DAC © RME
12.1 Subpage Settings
Source
The source of the analog output signal: Auto, SPDIF coax, Optical, USB, USB (Rec coax), USB
(Rec opt.). Default: Auto.
In Auto Mode any detected SPDIF Signal will have priority over USB playback.
Record SPDIF optical and Record SPDIF Coaxial activate the full duplex operation with USB:
The respective SPDIF signal is clock source and can be recorded via USB. The analog output
signal is the current USB playback, in case the sample rate is identical to the SPDIF input.
Line Output: Ref Level
Sets the reference level for the analog outputs. Choices are -5 dBu, +1 dBu, +7 dBu, +13 dBu
at the RCA output, referenced to digital full scale level (0 dBFS). The levels at the XLR output
are 6 dB higher, +1 dBu, +7 dBu, +13 dBu, +19 dBu.
Phones: Hi-Power
OFF, ON. Default: OFF. Reference level for 0 dBFS is +7 dBu at the output. With Hi-Power on
reference level is 15 dB higher, +22 dBu.
IEM: No choice. The output IEM uses a fixed reference level of -3 dBu.
Auto Ref Level
ON, Off. Default: ON. See chapter 19.3 for details.
Mono
OFF, ON, to Left. Default: OFF. The option to Left sends the
sum of left and right channel to the left output only.
Width
Defines the stereo width. 1.00 equals full stereo, 0.00
mono, -1.00 swapped channels.
M/S-Proc
Activates M/S processing. Monaural content is sent to the left, stereo to the right channel.
Polarity (Phase Invert)
Available settings are Off, Both, Left and Right. Inverts the polarity on the corresponding chan-
nel.
Crossfeed
OFF, 1, 2, 3, 4, 5. The Bauer stereo to Binaural crossfeed effect emulates speaker playback by
reducing the stereo width in the treble range. Adjustable in five steps.
DA Filter
Short Delay Sharp, Short Delay Slow, Sharp, NOS. The Digital to Analog Converter chip offers
several oversampling filters. Default is SD Sharp, offering the widest and most linear frequency
response and lowest latency. SD Slow causes a small drop in the higher frequency range, but
has a less aggressive (less steep) filter. Sharp and Slow are similar, but have a higher latency.
NOS is the filter with the smallest steepness and therefore affecting treble more than the others,
but offers the best impulse response. See the Technical Reference section for graphs illustrat-
ing the results in frequency response and impulse response.
Note: NOS deactivates the option De-Emphasis.
De-Emphasis
Auto, OFF, ON. Default: Auto. For manually de-/activating the DAC's de-emphasis filter. See
chapter 31.2.