^I'm not a physicist, but I believe that the reason for the flat sonic range is that CD audio is compressed (with an audio compressor, rather than a file compressor!) so that it sounds pretty much the same no matter what you play it on - so a cheap Taiwan CD player produces a freq range that will keep the kids happy.
Most audio these days is heavily (over) compressed to the point that it noticeably "pumps" - this is an artificial way of bringing an exciting sound to tedious music, and is done during the CD Mastering phase as well as during recording, production and mixdown.
Back O/T, I've been using a Project III USB Turntable - the purists may balk slightly, as it has a built-in pre-amp - but I quite like the crispness it brings to the top end without amplfying pops and crackles.
Fed direct to the PC (ie, no other amplifier colourations) via USB, the sound is pretty close to the vinyl original when recorded @ 192Khz/24-bit.
To do this, I'm using Sony ACID Express (a FREE program), since Audacity doesn't seem to record at this rate (at least, the version I currently have doesn't). I don't bother eliminating pops and clicks - they're there on the vinyl I own, if I really wanted to lose them, I'd buy another, better conditioned copy of the vinyl.
If I was feeling like a purist, I could level off the very top and bottom end of the EQ (no vinyl stores freqs above ~18khz or below ~50hz, TTBOMK, but somehow freqs in those ranges emerge in digital recordings like a kind of audibly undetectable noise) - but again, since I'm merely making a copy I can play without wearing out my precious plastic, the almost unnoticeable colouration can be lived with.
Granted, when you burn it to CD, you necessarily lose sound quality... but when you burn it to DVD-Audio, that's a different story.
There's nothing like owning the original, first pressing run vinyl, especially of classics from the late 1960s to early 1970s, when the sound was best - but 24-bit digital audio doesn't miss much