Turntables? — with a USB port, I think? I think that the marketing idea was to allow people to copy music from their old LPs and quality be damned. Then again, it might be okay.
Much better to feed the analog audio from an amp/preamp (from a turntable) into the back of the PC and digitizing it. I did that with a bunch of LPs and the quality is so much better than ITunes. And I don't think that it is related to the bit and sampling rate. Something else is going on. Maybe aliasing? — digital source being digitally sampled.
Sorry if I get a bit long winded here....
At one point, as a fun project, I was going to try to record in 5.1 and I needed three tape decks. I have all three but needed microphones I have some software that will make an AC3 surround recording for playback on a dvd player. A fun project.
I've seen those, but they always look cheap to me. I mean actual home-stereo, analog turntables (some of which are quite pricey and intended for DJing). As a musician, one of my future purchase plans is a decent USB analog-digital converter, so I agree with you that the best option is to plug a regular turntable into that.