Distortion from Airport Express setup?

I have a Mac desktop running Itunes with music encoded in Apple Lossless. It broadcasts to an Airport Express in the stereo room. I use the toslink out from this to a cheap DAC, from there to a pretty good stereo (Naim, Dunlavy). Slthough the sound quality is nowhere near that of a top shelf CD player it's pleasant enough for most purposes and I'm hoping that a better DAC will fix that down the line. The convenience is awesome. The problem -- transients are distorted, as if through a lightly applied guitar "fuzz box." It's most noticeable on loud piano passages and "average listeners" don't hear it unless I point it out usually, but from an audiophile standpoint it's really messing with the sound. I seem to get this also if I go with the Airport Express' analogue out (I haven't listened with headphones directly from the computer so I don't know if it's distorting there, but I can't imagine why it would). Has anyone else experienced this and could anyone suggest a solution?


Make sure that you have turned-off all of the DSP functions in itunes:
I had an issue like this--same kind of distortion--that turned out to be very strange and perpexing once I explored it. I'm still not sure what the root of the problem was, but it must have had something to do with some corruption in some arcane application support file in my user account (OSX, Panther) that interacted with iTunes. (It was not related to any signal processing functions within iTunes.) It did not have anything to do with Airport Express and Airtunes, so I would suggest you go ahead and plug some headphones into your Mac and listen for the same distortion.

I don't know that the chances you are having the same problem are very good, but if you hear the distortion coming straight out of the Mac, without Airport in the chain, you could try this next (if you're on OSX).

Locate an offending audio file in the Finder. Set the Finder window to column view. Then when you select the audio file, you'll get a little Preview pane that will let you play the file right from the Finder. Is the distortion still there?

Here's another diagnostic step. Set up a new user account, move an audio file that is giving you trouble into the iTunes library of the new account, and see if the distortion is still there.

If the answer is yes to these diagnostic questions, then you may be experiencing the same problem that I did, and we can talk some more. If the answer is no, then I wish you good luck on your search. You should be able to get good sound without any such obvious signal degradation through an Airtunes setup.

Don't know if the original poster is still trying to solve his problem, but I should make a correction to my message.

I said, "If the answer is yes to these diagnostic questions, then you may be experiencing the same problem that I did". I should have said, "If the answer is _no_..." (i.e., the distortion disappears when you try those two things).

Sorry about that.