@vonhelmholtz Just seeing this thread now and weighing in.
First, sample rates higher than 176-192KHz are nowhere near as important as the quality of the clock and the protocol. With that said, I would take a digital source with a quality clock maxxed out at 192KHz using AES over 768KHz USB any day. I am in the camp that believes USB is noisy and fatiguing in comparison. One case I can make is using USB from my $24K Aurender N30SA into my $38.5K T+A SDV 3100 HV. Where USB will use the T+A’s reference clock, even with 768Khz, I still prefer AES and the Aurender’s clock with 192Khz sample rates. The quality of the clocks in Aurender’s higher end units is very admirable and the N30SA (and the T+A DAC) is one of the reasons I’m debating so hard on whether I should give up on vinyl completely (you and I have discussed this). Many other endgame DAC manufacturers also prioritize AES, such as Berkeley, and AES is a professional protocol used in the pro audio / recording / mastering / production works. It is NOT a legacy interface.
Audiotroy mentions that Aurender can’t run Roon because it’s processors aren’t strong/fast enough. This is by design. By utilizing a low processing power architecture, Aurender can achieve lower noise floor, better separation, and just more of everything. Conductor is a proprietary platform to work its best alongside this low processing power environment. On the contrast, there is much debate about the “sound of Roon”. There was a fairly lengthy thread on this where I also commented on the elements that make a quality server/streamer (a robust linear power supply, low power, low noise, isolation, and clocking).
Also, I’m not aware of Aurender having any issues with native DSD playback. The Conductor platform allows users to choose whether they want native playback, DSD over PCM (DoP), or conversion to PCM. In this case, it boils down to the DAC’s supported formats.
Agree with others on i2s. There’s been a lot of hype, but implementations vary.