some inexpensive SDR dongles sidestep the question of getting a really good high-bandwidth ADC (still not cheap even today!) by just hooking up an intermediate frequency stage which downmixes RF to AF, and then you just hook it to one of the innumerable sound cards on the market to pull it into the PC for processing etc.
Wider bandwidth is wider bandwidth, the faster your sample rate the wider the range that you can sample. Iirc it's nyquist rate, so, with 384kbps rate you can sample a 192khz window.
Are you really taking a discussion about audio and making some sort of niche invented case of making a sound card be the analog to digital conversion from a software defined radio?
Even in that case 32 bit sampling is nonsense, the resolution of detecting voltages is never going to be accurate enough to need 4 billion different levels.
I'm actually quite serious, of the people who are buying really hi-fi audio inputs, it's not unlikely a large number of them are quite interested in the actual bandwidth of the input. They're using that sampling headroom for something else (oversampling).
Regulation and stabilization is a whole ""niche"" area of electronics called "voltage regulation" and yes, you can improve it a lot (and you can only do your best regardless of instability of the base). Actually a lot of audio engineers would be feeding it clean (linear regulated) power in this case as well. My Astron linear supplies are quite clean for radio and would be excellent for audio too.
USB optoisolator + linear regulated supply on a hub on the other side is something I've seriously considered for a nice SDR setup even short of that.
Again, of the people who buy this stuff, yes you will find a lot of people paying attention to the details and buying/building esoteric setups. Hams exist and the hobby almost inherently involves opening up the checkbook lol. Even decent audio gear is generally going to be $500-1000 most of the time.
some inexpensive SDR dongles sidestep the question of getting a really good high-bandwidth ADC (still not cheap even today!) by just hooking up an intermediate frequency stage which downmixes RF to AF, and then you just hook it to one of the innumerable sound cards on the market to pull it into the PC for processing etc.
Wider bandwidth is wider bandwidth, the faster your sample rate the wider the range that you can sample. Iirc it's nyquist rate, so, with 384kbps rate you can sample a 192khz window.