Made an interesting observation yesterday or whatever the appropriate word is with regard to hearing.
I've not done much listening to high resolution audio, but as I got a Marantz UD5005 multi disc player working recently I thought I'd compare its DAC to Z1010. I played an SACD with digital output going to my TV via HDMI and then from the TV to the amp using an optical link. Comparing this to the audio out from the SACD, I was surprised to find that I much preferred the audio produced via the amp DAC.
I know the digital audio output via HDMI is low resolution, so why did it sound so much better? Is the Marantz not a very good source compared to other SACD players? I've only done the test with one SACD so far, so maybe the recording is part of the reason?