Audio streaming drops only when using iTunes

My setup consists of an Airport Extreme (newest generation) serving as the wifi router and multiple Airport Expresses connected only to serve as hookups for streaming audio (ie they do not extend the network). I'm running 10.10.3 and iTunes 12.1.2.27. I've never had issues with my 2nd-gen Express that is located furthest from the Extreme, but the two 1st-gen Expresess occasionally drop their audio...sometimes coming back and sometimes losing it until I reconnect in iTunes. Whenever this happens I get the orange icon.

Recently I swapped out one of the troublesome 1st-gen Expresses for a 2nd-gen and I still have the same issues. This box is located directly below the room with the Extreme with very little in between to cause interference.

The most frustrating part is that this is only an issue when I use iTunes to stream the audio. If I run it through AirFoil I have almost no issues at all (even when using it to capture iTunes audio!). All of this leads me to believe the issue is software related within iTunes.

Anyone have any insight on this?