Airplay drops with airport express used as extender.

I currently have Airport Extreme connected to FiOS router and am using Airport Express to extend network. I have three Libratone speakers connected. Whenever I try to use multiple airplay speakers with iTunes I have constant audio drop. Using one speaker or disconnecting the AE seems to correct the problem, but without the AE to extend the network one of my bedrooms has nearly no wifi.. I know zero about computers. Any suggestions.