Why not just get two stereo 535? I have used Monoblocks, Stereo and Quad power amps. Monoblocks are the most flexible. Stereo next, and Multichannel last. At the moment I use three stereo amps (Carver ZR1600) like monoblocks biamping three speaker systems. Multichannel amps tend to be heavy and hard to move around, although this might change with digital technology.
The 535 is a bit short on power but I found them OK when used to biamp.
The 535 is a bit short on power but I found them OK when used to biamp.