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.  

In your 2 choices, I would lean towards the Classe CAV 500.  It definitely has a much beefier power supply.  Since you are looking at the "older" 5-channel amps, I would also suggest looking at the Krell TAS.  There's one up for sale for $3098.  The Krell has more power supply and brute force then the Theta.  I don't know how it compares to the Classe.

I have the B&W speakers too, and you really want a high current muscle amp to make these speakers sing.  Look for massive transformers and capacitor banks in your amp. 

The Theta Dreadnaught has big transformer, but smaller power supplies on each amp board.  The Anthem P5 had very small individual transformer/power supplies on each amp board.  In my experience, smaller power supplies mean less brute force in the bass/midbass area.  Please note that these are not bad amps, but the huge power supply amps have an edge in low end muscle/body.

I don't know your space requirements, but another idea would be to look for a really hefty 3-channel amp and then use your Primare for surrounds.

Please don't kick me here for this next suggestion, but I have found that the Emotiva monoblocks mate very well with the B&W speakers.  I'm using big XPR-1 monoblocks for each of my three front channels and smaller XPA-1L for surrounds. 

If you had space, you could buy five of mid-level XPA-1 monoblocks and do Isoclean fuse upgrades.  Alternatively, you could look for an XPR-2 and XPR-3 if you only had limited space (also with Isoclean fuse upgrades).  Either of these options fall within your $4500 budget. 

Thanks everybody!  I wound up snagging a CAV 500 for a very good price.  Question, though:  I was planning on placing it in my entertainment cabinet, which has held my Primare amp without a problem.  My concern, though, is that while the amp will have plenty of overhead clearance, there will only be roughly an inch of clearance on each side.  One side has holes drilled for ventilation, but the other is solid.  The back is open.  What's the risk here, and is there anything I can/should do to mitigate it?  It's probably impossible to place the amp anywhere else--challenging room.
I don’t see a problem there. Heat rises. An inch is fine on the side if you have good space over the top of the amp.  Let us know how it sounds!
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Bryston 9B-ST.