Very interesting questions raised, at least in my mind - if our mics only record up to 20kHz, what's the point of being abel to playback or record higher than 20??? How about your playback freq. range???
yes, it is very interesting. a few different things going on here, 24 bit vs 16 bit, and then the whoel sampling frequency debate.
IMO, 24 bit is definitely worth it. the added low level detail (in both the music and the ambiance) makes the recording much mroe realistic. It just makes it that much easier to close my eyes and imagine that I'm back at the show. Come on Nick, first you say that 24 bit isn't worth it, and 16/44.1 upsampled at playback to 24/96 sounds almost as good as real 24 bit. then you change your mind think 24 bit really is the way to go. and then you get the Oade mod PMD-660 and think 16 bit is all that.
I'm a strong believer in the advantages of 24 bit, regardless if you think it makes the background conversations stand out more.
now, what Terry was talking about with Frequency response. there is more reason than just frequency repsonse to increase the sampling rate. I've read (sorry, I'm at work and don't have time to look up articles to link to at this time), but I've read that the human ear can detect time differences that are smaller than 1/48000th of a second. From that logic, a 96kHz recording will be able to more accurately represent when a note actually begins, while that exact point in time is missed somewhere between 2 samples from a 48kHz recording. (I'm sure that I'm not describing it as clearly as I would like, perhaps someone else can chime in and help out as well).
So, does that sampling difference make an audible difference? well, I've only done one non-scientific comparison of a 24/48 recording vs. 24/96 recording. based on that comparison, I'd say the difference is subtle, but I was able to pick up a slightly more defined and clarity when listening on my grace 901 > grado rs-2 headphones. but very subtle. subtle enough that I'm more than happy to record at 24/48 until 8gig CF cards are cheap enough.
but do I think 24 bit is worth it? absolutely. huge improvement over straight 16 bit recordings.