I dunno, Kijanki, I randomly looked at two good power amps in JA's testing, a Moon and a Pass, and they were both had measured s/n ratios of about -84db at 1 watt, which is actually excellent performance. You keep forgetting that most power amps have about 30db of gain. Measuring s/n ratio at full power is sort of cheating for marketing's sake. A speaker with 95db/2.83v/1m efficiency, like my old Legacy Focus, will let you hear the hiss from such an amp rather readily. So I still contend that for listening the amps are the limiting factor, not well implemented 16/44.
As for your comments about Nyquist, it would seem your real thesis is that digital reproduction isn't very good, even with a DAC1. I still wonder, why does it sound so good if you're correct? I'm missing something.