Matrix M-Stage HPA-3U+ DAC/Amp

Your Nyquist assertion is accurate, I didn't mean to be vague. By "at that level" I meant greater than the general threshold of human hearing at 20kHz. I've had gear claiming 40khz and don't really notice much on the top end. The only consistent benefit among properly sourced hi-res I've been able to discern is a clearer fundamental, slightly better transients and a greater sense of the recording space (close mic, live, small venue, etc..). Again things probably not worth it to most folks, I will argue CD quality beats lossy compression until I die however.

actually, due to the Nyquist theorem, in the best case scenario a device with 192kHz samplerate can only playback up to 96kHz. You effectively need the sample rate to be twice the highest frequency you wish to produce. The higher samplerates such as 96k and 192k are frequently utilized not to garner ultrahigh frequency information, but rather to move the corner frequency of the antialiasing filter, and the aliasing artifacts themselves out of the range of human hearing. This is not because you actually hear the filter. But it can induce phase smear in the top end which may sound brittle and harsh. I actually own equipment with 192k samplerate, and 50k bandwidth. Even with my crappy hearing I can hear a benefit. Mostly a very clear treble with a distinct edge on details, without sounding liek a treble knob has been cranked up.

Hertz is a measure meaning "cycles per second". In the case of 96k/192k that is referencing how many digital sample cycles were captured per second of recording, either from a different recording/tape or live performance. 20 Hz to 20 kHz is the range of sound frequencies the average human being can hear. In this case that is the rise and fall of the audio sound wave. Bass frequencies are longer so it takes them more time to complete a cycle , hence the reason bass frequencies are on the low end of the range. While a 192kHz sampling frequency does enable the capturing of audio frequencies at that level it is not the sole benefit. I am certainly not touting hi-res audio for all but having spent 15 years or so playing with the different formats of hi-res I will say I can generally hear a slight positive difference. Definitely wont be worth the extra expenditure to everyone or in all cases. A lot of "hi-res" tracks offered have questionable sources.