So DSD over PCM 1.0 is the correct setting”. However, with USB I cannot send anything above 48kHz to my processor. There are no problems over HDMI, all the high res PCM formats play. The DAC recognises it correctly and decodes the DSD signal. A 'premium' paid version of this excellent free software player has just been released, new additions include iZotope 64-bit processing and dithered volume control via MBIT+ (same as Amarra), as. I use Audirvana 2.0 on a late 2009 iMac connected to my Emotiva XMC-1 processor via an asynchronous USB port and via HDMI. It is true DSD signal, just that OSX thinks it is PCM. “DoP is a method to encapsulate DSD native signal in PCM stream. This may explain why a DSD 512 DAC can stop at DSD 256, and DSD256 DAC can stop at DSD128.”
This can reduce the maximum DSD frequency that can be used with DAC by half compared to the frequency that can be reached under Windows. Please note : The “DSD over PCM” protocol requires markers to identify the signal as DSD, so using this protocol requires double the bandwidth compared to the native DSD signal alone.
However, if your DAC is not DSD compatible, Audirvana Plus will perform downsampling to PCM using a very high quality 64 bit algorithm. AudioMacBook AirMarantz HD-DAC1DENON PMA-2000REB&W 804SD Mac Music PlayerAudirvana Plus Ver.2.2.5 (24bit/192kHz Up-sampling) USB CableAudioQuest USB Carbon RCA CableAudioquest Yukon SP Cable. In order to get the best possible result, you need to use Audirvana Plus with a Native DSD DAC. “To listen to DSD files from a DAC, Audirvana Plus transmits the DSD files to the DAC using the “DSD over PCM” protocol that requires markers, and using this protocol requires twice the bandwidth over the native DSD signal only.
The following is from Audirvana’s designer in relation to DSD/DoP: