Bi-Wiring from sep. amp versus an a/v receiver

I was wondering (sorry if this sounds dumb)... but bi-wiring. I want to bi-wire my Mirage OM-10 speakers. I have an Onkyo DS-TX797 which puts out (according to manufacturer specs -- 100 WPC). I have a friend who has a B&K ST2140 (rated at 185 WPC into 4 Ohms) that I could get from him for a really good price. Now, I have always heard that receiver's WPC ratings are usually not correct and usually overstated. So my question is.... would I do better by bi-wiring the speakers to the B&K?
THANKS