what is jitter supposed to sound like?

The Stereophile CD is a good idea. If you want a verbal description from someone who has battled it a bunch, I would say that it makes everything less distinct. It removes the fine details that create depth cues and the quick, high frequency transients that make percussive and plucked instruments sound real and exiting.

Gmood1, you are definitely on to something. One effect of power supply noise and ripple is that it changes the threshold at which digital gates switch. This can have the effect of advancing or delaying a digital transition and thereby increasing jitter.

Bombaywalla, good point. I found that jitter was the problem in my system accidentally. I was building my first system in 20 years and everything was new (to me). I tried everything I could think of but the sound still seemed dull and lifeless. In desperation, I thought I would see what equalization might accomplish so I borrowed a dbx Quantum mastering processor. While it was still in bypass, the sound snapped into focus like I'd never heard before. I finally figured out that it was the huge reduction in jitter that caused the improvement. I've found a much more cost effective way of creating a low jitter signal now but the symptoms I was hearing could have come from a multitude of sources.