Did you try listening from a music streaming service (pandora, MOG, etc) using 3G/4G/EDGE seems to be the culprit when it comes to interference. At least on my turdy E6 with an iphone4>L3>E6>____. I hope my just ordered Arrow is at least slightly better on that front since I like pandora once in awhile.
EDIT: Yea definitely go for the L9 I'm actually looking for a lower profile LOD right now cause the L3 is too bulky
I usually listen to Apple Lossless files stored on the phone, but I do use iTunes match over 3G and WiFi, haven't noticed too much interference. YMMV