It's not possible right now, and - most important - not needed at all.
Hi MC. I want to discuss this issue further. I'm not a fan of DSD. But having `native` (means unpacked, or not done via dop) DSD supported in alt setting is beneficial in DSD playback.
Why? Because in most players, seeking to a different position in a track will usually go through a restart signal (stop, empty the buffer, fill the buffer with new data, start). This usually goes well in PCM or `native` DSD, and there's no hiccups in the playback.
However, in DOP's case, things are different, because the device assume the incoming signal is PCM by default, so the detection algorithm has to be rerun to find the DoP Marker (0X05/0xfa) for quite a few samples until finally being confident that the new signal is a DoP one.
That's the reason that in almost all players, a hiccups/noise will be heard on RME ADI-2 Pro devices when seeking to a different position in a dsd track. This is because the playing mode is switching to PCM and back to DSD. If usb alt setting dedicated for DSD is supported, and the dsd data can be sent directly, no DOP detection will be needed, and the hiccups/noise can be avoided.
Page 43 of the ADI-2 Pro manual (19.3 DSD Playback) said this is an inherent issue of DSD playback, which is not true. DACs with proper `native` implementation are noise free during seeking or track changing (as long as they are of the same sample rate).
By the way, I notice a strange behavior with the latest firmware. in page 44 v2.3 of the user manual (19.5 DSD Level Meter), AES and SPDIF shows -24dbfs while playing DSD. I notice the same expected behavior when playing DSD64. However, When switched to playing DSD128 or DSD256, it's the AN input that shows the volume meter, rather than AES and SPDIF output. Is this a bug?
As new forum member (and new RME user), I want to thank you wholeheartedly for creating this wonderful product. This is truly the most amazing audio interface I've ever used.