Hmmmm. Something is not right here.
$50 portable CD players incorporate electronic antiskip mechanisms by reading ahead 5-10 seconds and storing the data in a buffer--and they are far from audiophile grade transports or players. The challenge of high fidelity playback is not limited to problems with spinning a disk, and it is absolutely no surprise the today's PC hard drive configs don't compete with EMM Labs gear.
CD audio encoding is surprisingly complex (e.g., see
http://www.ee.washington.edu/conselec/CE/kuhn/cdaudio2/95x7.htm). And one result of this is very high bit-for-bit fidelity. It is true that the CD Audio redbook spec has less error correction that CD-ROM--i.e., it "allows" a certain level of interpolation of data--but in general it seems that this is not the problem (see a classic at
http://stereophile.com/reference/590jitter/index.html); good transports or bad, you can be pretty sure that your DAC is getting a bit-perfect feed.
The next area to look at is jitter. This is any variance between the actual data clock and an ideal clock. Transports, hard drive controllers, DMAs--they are all going to have jitter, so replacing a transport with a hard drive will not remove this problem. It may allow it to be mitigated--or may be not: PCs are hostile environments and jitter is measured in *billionths* of a second.
There is no doubt that mitigating jitter can improve audio reproduction, but in Harley's article at the above URL he looks at CD tweaks and found audible differences yet no difference in jitter; i.e., something other than jitter--at least as he was measuing it--was causing an effect on his "perfect sound forever."
I think the problem is in the CD format when it leaves the factory or the website, and you are doomed before you ever bring it into your house. Here's why: The CD spec does not store the time information along with the amplitude. It just stores the amplitude, and the clock is recovered from the signal. If they had spec-ed it in packets like TCP/IP embedding clock and amplitude, then you could recover ALL the data, amplitude and time, bit-perfect, from a CD, a website, even a carrier pigeon--the transport mechanism wouldn't matter. But the clock is implied in the signal, and that means that it has to be re-created at playback. Ever wonder why transports make a difference on playback? It's because the servo is jerking the DC waveform and introducing trash in other parts of the CDP; same with digital cables: because the clock is not "data" per se, the way your DAC gets the data through your cables from the transport can affect the time reconstruction.
I think computers have a lot to offer audio, and, like digital amps, may drop the price floor on very good reproduction. But for *really* good reproduction, it'll be years before anything beats a CDP or TT.
