Hi Danny, I setup some listening tests today. While I can’t test blindly (There are a few places I have to go in the interface to change it), I can give it a good shot. I used to be in the industry and developed (not programmed) both digital audio hardware and software, so I have a firm grasp of what to listen for when comparing digital streams. I used two pieces that I know well. Both I have heard 2nd or 3rd generation tape masters of, have also extensive experience with them on vinyl, and have high resolution versions to compare.
With 16/44, 24/192, then with DSD64. I used headroom management -16db compared to no headroom management and -16db DSP Volume. I am using a recent Allo USBRidge Signature with Ropieee installed to my R2R DAC without upsampling.
On PCM files, I could reliably hear a small but significant difference between DSP Volume and Headroom Management. The DSP Volume engaged had a slightly flatter soundstage, a bit more edge/sibilance on vocals with them pushed to the front a bit more, cymbals spat more than rang, bass was a bit less dimensional and tuneful. Not a big difference, but I could hear it. With the 16/44 files the difference was stronger.
BUT I hit a big snag on the DSD files. I was listening to the difference and it was bigger, and I kept saying to myself, this sounds more like PCM. After a few tries I looked at my dac and DSD was not showing, it was PCM! Looking at the signal path, it was indeed converting it to PCM at the beginning of the chain! I wasn’t expecting this, and I can’t use DSP Volume in this scenario, I listen to a lot of DSD. Could this just be unique to my setup? I am including screenshots.
