But that is now how digital audio works.
yeahahno. My interest is how most effectively to exploit the teachable moment.
More bits doesn't give more resolution - or at least not in the way most people are thinking about resolution.
Number of bits just sets the level of the noise floor. If you have a full scale signal, that is well above the noise floor. A low level signal is closer to the noise floor.
You skipped a step: calibration, or level setting.
"Resolution" in the sense that I imagine paulg1 was imagining it -- stair steps or preferably, we hope, lollipops -- is quantization which gives us the quantization noise level relative to FS. Now, if FS is appropriately set in the playback system and environment for the human audience then the difference between 16 and 24 bit noise probably won't be audible. That's what I meant when I said (above) that the low resolution of quiet signals "doesn't matter".
Even here I'm making some nontrivial assumptions. I'm hoping to glide past "appropriately set" and "probably won't be audible" without having to elaborate and I didn't even mention the signals, are they musical, acoustic, synthetic, how were they mastered?
Let's say I record Cage 4'33" in a super quiet environment with the quietest mics, amps and converters. I include that on a release with some other tracks of normal loudness. As producer of this recording I want the technical noise to be minimized and the performance to be very serious and the mastering to be realistic, so the peak for this track on the release will be very low. But I anticipate the listener might turn the gain all the way up to hear the pianist's breathing, movements, perhaps even the heart beat -- it's 4'33" so who knows what you might find. Might want this to be a 24-bit release to allow listeners to turn it way up and get that "nice resolution" of the very quiet performance, i.e. to not have to listen to 16-bit quantization noise with the playback gain set very high gain.
Questions about what dB SPL corresponds to dBFS in playback and how the track is mastered come into this. My previous remark about riding the volume control to listen to the quiet bits louder was all about this, just not as explicit.
I think this kind of thing is interesting, don't you?