When I first did some reading about the Pono player I ran across this link:
http://xiph.org/~xiphmont/demo/neil-young.html
I thought it was really interesting and made me rethink my SACDs.
The only thing that does not ring true is his comment that 24/192k is inferior to 16/44.1k. More is more, so more bandwidth and more dynamic range is not really a sonic compromise. It is inferior for "cost/benefit", but not for "price is no object" demonstrations of excess (which is what audiophools live for).
I do agree that 16/44.1k is adequate for us mere humans who probably can't perceive any audible difference between the two, (assuming proper execution of both).
His example of providing significant false signals above the normal human hearing range that causes IMD in marginal audio paths is IMO a straw man argument. In nature the energy content of real signals that high frequency, dissipate rapidly in air so would naturally be very low level. Also if consumers were willing to pay for 24/192k media (storage or download bandwidth), they could also pay for a commensurate speed playback audio path so should not experience IM distortion from reproducing that bandwidth.
JR