Airtunes is giving me dropouts
I had this problem several months ago and was able to solve it by disabling the built-in iTunes equalizer.  Just uncheck the "On" box.

Not guaranteed to work for you since there are so many factors that could be affecting it, but it worked for me.  Hope it helps!





EDIT:  A couple more notes...  I have a pre-N Airport Express (circa 2008) wirelessly "attached" to a Time Capsule base station (essentially an Airport Extreme with a HDD built-in).  Before, when I was having this problem, I had my Express extending my wireless network.  During the course of correcting this problem, I changed it to simply join my network and NOT extend it.  I'm not sure if this contributed to the solution, but I just wanted to mention it in case it turns out to be significant.