I own a bunch of hi res downloads and SACDs from both HDTracks and Acoustic Sounds. None sound better than a well mastered PCM 44.1/16 disc or file. This is just my personal observation. To me, hi res sounds different, maybe even louder than rebook, however, not necessarily better. But, there is an inaccuracy in the sound that I just can't define.
Yeah, technology continues to get better, but human hearing is fixed, so the 44.1Khz sampling is all that's necessary as it offers a bandwidth of about 20Khz. If you play with the Nyquist formula it includes guard bands and lock possibilities, but ends up about 20Khz. I know I can't hear that high, and not many can. No reason to sample any higher as far as I can see. You also have to consider that higher bandwidth systems can pass signals that may exist above 20 Khz (noise from switch-mode power amplifiers, etc). There's no sensible reason to pass this information to the digital signal.
When you consider the bits, a true 16 bits is quite hard to achieve. Everything has to be perfect. The theoretical noise floor for an A/D converter is fixed and a function of its bit resolution. A 16 bit A/D converter is 98 dB, and a 24 bit is 147 dB.
Regardless of the input amplitudes to an A/D convertor, the LSB and many bits above that reside in the region of thermal noise that the resistors around the A/D are generating, so most of those bits are lost in the noise, and that's with a pristine analog recording (which is a huge factor in this equation). So a 24 bit converter is 24 bits in name only, and they'll be lucky to get 16 bits out of it.
So anything more than 44.1K sampling is beyond human hearing, and anything beyond 16 bits is sacrificed to the noise floor.
The fact that you tell us that:
"None sound better than a well mastered PCM 44.1/16 disc or file" tells us that you are a critical and honest listener and not persuaded by the hype.
brucek