Hi. I am having problems getting feedback which builds up gradually whilst building loops. My setup is:

guitar+mic > RC-20XL > PA

I have tried adding a mixer between guitar+mic and the pedal to improve the sound quality, but it is still a compromise on sound quality and I still get feedback which I think comes through the mic during the loops

Any help
As much as I love this pedal as a songwriting tool, I've never really found it useful in a live setup. If you don't get the loop to start and stop EXACTLY the how it should.....
Fender 72' Deluxe Tele
Schecter Damian Elite 7
Fender '62 Reissue Jazz Bass (MIJ)
Peavey XXX 212 (back on the East Coast)

Macbook Pro 15" Retina
Logic Pro X 10.0.7
Revalver 4
LePou Amp Sims
Ignite Amp Sims
RedWirez Impulses
I have the live situation pretty much under control as far as getting the loops to work how I want them... the only thing is the loss of sound quality. The noise surpressor will sort out any hiss, but this is not my mail problem. I read lots of reviews about this pedal and most people rave about it's sound quality... so I don't understand why I notice such a difference. Do most people use a mixer in the rig in addition to the main PA?