If the WAP was close enough and strong enough it will reduce your maximum range but it's not likely causing any audible audio problems. You most likely proved that out by switching the channels. If the noise had gone away when you switched channels then it would have called for more investigation of the WAP.
It is possible that it could be causing noise directly into your instrument.
I have not been able to reproduce the problem at home. I also tested with an WAP near by.
Last night the system worked flawlessly during a gig.
I'll assume the problem is solved!
Alse see thread http://line6.com/community/message/284826#47085