As I've mentioned before I recently finished ripping about 8000 songs to MP3 (mostly 192-320 VBR) and when you rip that much music to a lossy format it makes you a bit paranoid. So everytime I hear any weird sounds I go chasing after them.

Recently I went chasing after several cases of "crackly" distortion - two of them were during female vocals (Stevie Nicks, Joni Mitchell) and one was during a guitar solo in a Doors song. In each case I went back to the original CD and played it on two different CD players and also listened to both CD players on two different headphones. I was relieved to hear the exact same crackling on the original CD on both players! (so at least it wasn't the rip) I even enlisted my poor wife to confirm this.

But now that my ears are "tuned into" this peculiar distortion I hear it more often than I'd like to. What causes it? Can anything be done to filter it out?

Probably just crap CD mastering. A lot of CDs are just turned up to make them louder causing clipping. You should get a refund for them!

Saying that you hear "crackly" distortion is about as informative as the reports in a lot of audiophile equipment reviews. The symptoms you hear may be real, but there is no way for anyone else to know what you mean. Audio editors provide tools to ameliorate some problems, while there is no way to effectively do anything about others. Without knowing exactly what you are hearing, wild speculation is the only response possible. Posting samples is the only way to accurately communicate.

I'll try to do that. The reason I didn't initially is that when I searched HA and also Googled the web I got zillions of hits. It's apparently a widely-discussed and recognized phenomenon so I figured most people already knew what I was talking about. The problem, as I mentioned in above, is that I was unable to find any consensus about its causes or treatment.

Well, this a clear case of bad mastering or in case of old music just bad recording equipment, or both. Remasters CDs or new compilations are usually even worse than the originals because they clip all over the place. Try googling for "loudness war"

Real bit errors, intentional errors (which some CD makers have inserted in order to error-out CD-rom drives), clipping and wraparound are the most likely things that create "crackling".

Is this on a high-level part of the signal?

If it's not, it's not the last two.

I've had occasion to simulate bit errors, they sound like random crackling noises.

But it's really, REALLY hard to get bit errors to either your rip or the CD player.