Superb answer. Very nicely put, and I am grateful for your input and experience. I encounter too much dogma ("You just can't because blah blah... ") when, as you so rightly say, the answer is might
. I'm sure it would be ideal, when recording silence, to see no movement on the level indicators whatsoever. I'm not sure if that ever actually happens on real pro equipment (?) but it certainly doesn't on my PC, with either interior (RME) or external (Echo Audiofire) interfaces --- but the extent to which this "noise" has to be amplified is pretty enormous if one wants to actually hear it.
I've been learning a lot, recently, both about the basics of sound, and the differences between what we hear, what we think we hear, what is real, and what isn't. It is fascinating stuff, and one has to be prepared to actually let go
(in a healthy way) of absolute belief in one's own senses. I now, with respect and accepting that they are sincere, utterly disbelieve some of the things that I hear from "audiophiles" (hey, perhaps they aren't really saying it!
--- and I apply the same sort of (hopefully healthy) scepticism to my own experiments and observations (such as ... I can now hear the vocalist in this concert, but no-one went near the mixing desk, or moved the mic, so it must
be my brain that adjusted).
I haven't listened to the "built-in" in my current PC ... but I'd be surprised if it wasn't a lot better than the one I started my PC-audio journey with, and possibly better than my first add-in card. For the casual recorder/listener, they have come a long way.
About compression, I'm not at all sure how much I can hear, because, except at low bit rates, it seams to me to be the cumulative effect of listening (rather than specific can/can't hear) to compressed (as in MP3; as so often happens, the world has probably not chosen the best method available) music or speech. It results in a kind of fatigue, getting fed up, wanting to switch off, sometimes even when I'm enjoying the content (Hello BBC Drama!).
At the moment, I'm trying to work out if I can, or can't, hear the difference between 41.1Khz and 9600. I have age-related hf hearing loss: I may never know if there is a difference or not!
But, for those who are not in the least interested in this stuff, I've got no problem if they just want to stick a tape in a machine, and get a thumb-drive full of MP3. Convenient --- and almost certain to be a heap better than those machines that copy from one cassette tape to another!