Best used five-channel amp?


I'm looking to upgrade my trusty Primare A30.5 amp to something a little more muscular a higher end.  I have a Classe Sigma-SSP processor and B&W 804s units for the front and an HTM3s for the center.  Does anyone have recommendations for used units?  I've been thinking about the Classe CAV 500 or the Theta Dreadnaught.  I'd like to keep it under $4,500 or so.  Thanks!
win200
NAD M17, it's a beast.  I know it's a seven channel but you can bi-amp;). Anyway, I am using it w/the new 804D3 in a 7.1 setup and it makes those beauties sing!
I don't know about "best" but an Anthem P5 is a beast at 325/ch.  New around $8000.00 used in the $4000.00 vicinity.

Bill
If you can find one, CAL (California Audio Labs) MCA-2500.  It's a beast and can put out $500w/chan.