DM,
First off, I want to thank you for your many detail and insightful post on the AMR DP-777 Dac. I too am a happy owner of this DAC these days and this is the best sounding dac I've owned. I don't have the experience you had with the many high-end dac's that you've survey or the $30K vinyl playback set up you have.
I've gradually over the past decade swap through more than a half dozen dacs with the most recent ones being the Linn Majik DS, Benchmark USB, Wavelength Brick and multiple Musical Fidelity dacs. I only found the Linn and AMR providing like level of quality playback via the USB interface as their spdif. However, the AMR was clearly a class above the Linn and I'm fond of much of the same qualities you've highlighted for the AMR.
You've mentioned on this thread that you would comment on the USB cable recommendations for your DP-777 setup. I'm still using the stock USB cable, as it is the best I've found thus far. Haven't spent real dollars on this aspect yet but hoping to obtain meaningful improvement without breaking the bank :-)
Part of my hesitation is my computer analyst background causes my skepticism on whether a mega buck USB cable would have noticeable vs a threshold quality USB cable (reasonable shielded/quality construction), if a DAC has implemented proper Async USB interface. I can imagine the USB cable could have impact if it was a long run, but since I'm just using a 1M length run, I'm curious if the impact would be as noticeable.
I'm curious if you had chance to experiment in this area yet and what was your observations.
Gerald