That's a cool receiver forum; thanks Armand
I have a 507 that I've been gushing over in my own thread around here

I use M&K S125s for fronts, a S100B for center, an MX150IITHX sub, and two pairs of SS150 tripoles for surrounds. It sounds incredible!
As for the whine, I only hear a bit of processor whine thru one of the surround speakers but not when the unit is actually playing anything. The whine level is VERY low and you have to stand next to the speaker to hear it. I wouldn't let this stop you from getting such a fine receiver, though.
For me, the whine is a non-issue since it's not there when it counts; during operation.
Cheers,
Dan