Operation and Usage
Playback
The HDSPe AoX-D can play back audio data in supported formats only.
In the audio application being used, HDSPe AoX-D must be selected as output device. This can often be found in the Options, Preferences or Settings menus under Playback Device, Audio Devices, Audio I/O etc.
| To ensure that system sounds do not interfere with audio playback and recording, it is strongly recommended to switch off all system sounds or routing them to a different audio interface. Also, the HDSPe AoX-D should not be the Preferred Device for audio playback, as the operating system might attempt to play back audio at an incompatible sample rate and yield errors. |
Consult the manual of your digital audio workstation for details on how to set up the correct driver.
Increasing the number and/or size of audio buffers may prevent the audio signal from breaking up, but also leads to an increase in latency (i.e. output signal is delayed).
The HDSPe AoX-D allows sample rates of up to 192 kHz. The number of available channels is reduced to half of the advertised channel count at double speed (DS, 88.2 kHz and 96 kHz), and one fourth of the advertised channel count at quad speed (QS, 172.4 kHz and 192 kHz).
| The audio application cannot control the sample rate using the WDM or ASIO driver interface. Therefore, the driver of the HDSPe AoX-D includes a way to set the sample rate globally for all WDM devices within the Settings dialog, see Configuring the HDSPe AoX-D. |
Surround Sound (AC-3/DTS)
AC-3 / DTS Pass-through
When playing back files that include an encoded multichannel audio stream (for example using software like PowerDVD®), the audio can be passed through to any AC-3/DTS capable receiver via the HDSPe AoX-D’s digital outputs transparently.
| Encoded AC-3 or DTS signals sound like chopped noise at highest level. Ensure that the volume is turned down before starting playback to confirm that the signal is properly sent to a device that detects and decodes the signal. |
For this to work, the playback software has to be configured accordingly so that it would not attempt to decode the signal by itself. Consult the software’s manual for details on how to configure AC-3 pass-through.
Decoded Multi-channel audio
Some media players will automatically decode embedded surround sound signals. The HDSPe AoX-D must then be configured as the preferred audio device in the operating system sound settings.
| Newer versions of Microsoft Windows™ have removed the corresponding Codec and it must be installed manually. |
Multi-Client Operation
RME audio interfaces support multi-client operation. Several programs can access the HDSPe AoX-D at the same time. It is even possible to access the same channels with ASIO and WDM drivers at the same time. As ASIO does not use real-time sample rate conversion, all active ASIO software has to use the same sample rate.
However, a better overview is maintained by using the channels exclusively. This is no limitation at all, because TotalMix allows summing of several software playback channels by creating a submix.
Inputs can be received by an unlimited number of WDM and ASIO applications at the same time, as the driver simply sends the data to them simultaneously.
RME’s sophisticated tool DIGICheck operates like an ASIO host, using a special technique to access playback channels directly. Therefore DIGICheck is able to analyse and display playback data from any software, no matter which format it uses.