@kray on the D-1 I tried A, B, C 2nd Order Harmonic Distortion filters. The A & C filters were only used when burning in the DAC and the sound was fatiguing. Once burned in I removed 2HD filters went naked for a while. However, I found I wanted a bit of warmth when using headphones, so I am now settled in with filter B at Level 4. I even use that with 2-channel. In fact, the D-1 is really only used with 2-channel (Livingroom) and the MA3i will be used with both 2-channel (office) and headphones.
I asked John La Grou, the D-1 designer, to help end users out by posting a page on their web site to explain the sonic attributes of 2HD A to F filters. I have no clue as to how they individually differ from each other, John said that was on their ToDo list.
BTW - do you have a D-1 DAC in the house?
@audphile1 I had to reinstall my Qobuz desktop app and I am now able to stream to the MA3i from Qobuz by-passing ROON. I do not have time to do a lot of testing, but I tried 1 song that I find can sound too hot on playback, that is DREAMS by Fleetwood Mac. On the MA3i streaming from Qobuz there is a bit more energy on top. Not too much to make it fatiguing but noticeable. On ROON, this is slightly tampered down. I do not feel like I am losing resolution (hard to tell) but the sound is a bit less hot on top and I prefer it (for this song).
After listening to another song, there is definitely a subtle difference, and I am not sure which I prefer. I am listening with the CODA #16 and the Yamaha NS5000 speakers.
I do not have a direct connection via USB to my D-1 DAC, so I am not sure how I can get the Qobuz app to stream to the D-1. I think I need Qobuz connect to be setup to my DAC. My Sonore OpticalRendu which I use to stream to the D-1 is the ROON ONLY version so that will not work.