RME Audio ADI-2 DAC, User Manual

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48 User’s Guide ADI-2 DAC © RME
26. General
The ADI-2 DAC operates in
Class Compliant mode (UAC 2.0), a standard that is natively sup-
ported by operating systems like iOS, Mac OS X and Linux. No proprietary drivers are required,
the device will be directly recognized.
The ADI-2 DAC provides iOS devices with the professional I/O connections they lack. Profes-
sional balanced and unbalanced line outputs, two Extreme Power and IEM headphone outputs
that excel with both high and low impedance headphones, extensive gain and level adjust-
ments, SPDIF input, PCM playback at up to 768 kHz, and DSD playback at up to 11.2 MHz
(DSD256).
The ADI-2 DAC does not supply power to the iPad/iPhone. The latest Lightning to USB 3 Cam-
era adapter from Apple includes a Lightning socket to connect the standard Apple power sup-
ply, allowing to charge the i-device while it operates in Class Compliant mode with the ADI-2
DAC.
27. System requirements for iOS Operation
x
Any Apple iPad with at least iOS 5 or an iPhone with at least iOS 7
x
Apple iPad Camera Connection Kit or Lightning to USB adapter
28. Setup
Connect the USB cable to the Camera Connection Kit/Lightning adapter. Start the i-device and
plug the Kit/adapter into the i-device’s socket. If everything works as expected, the unit will be
used for all audio I/O. Audio playback in iTunes will automatically be performed by the ADI-2
DAC, using analog outputs 1/2 and 3/4.
Note: The i-device’s volume control is inactive during USB operation.
29. Notes
In Class Compliant mode the default clock mode is
Internal
, and iOS typically sets the highest
available sample rate. Any app can change / set the sample rate to a desired value, but not all
apps include a choice to select one. Setting the ADI-2 DAC (and with it the i-device) to slave
mode by selecting the SPDIF input as clock source, the ADI-2 DAC will be synchronized to the
external digital sample rate. With a wrong external sample rate heavy audio noise will occur.
Without an external signal the ADI-2 DAC changes to its internal clock, with the sample rate set
by iOS or the app in use.