200w/ch stereo amps: best 1 for under 2000 used?

The sound-level at the "other end of the room" is not necessarily relevant. It's the total "volume" (Cubic Feet) of the room that needs to be pressurized and filled with sound.

If you're considering the EAD five-channel amp, I would also suggest that you look into the Citation 7.1 four-channel amp - 150wpc X 4 or 450wpc X 2. (Jeff's Sound Values has B-stock for $1095 ea.) You could actually buy two with your budget and bridge them to 450wpc and vertically bi-amp them as you've suggested. This might be a very nice solution.

In addition, I would recommend (for the money) a longer run of speaker cable vs. a longer run of interconnects. Others may disagree, but you can purchase a decent quality speaker wire in a long run for less money than a good quality interconnect of equal length. Plus, the longer the run for an interconnect, the more critical high-quality becomes to avoid loss of voltage, RFI, EMI, etc.

My two-cents. Hope it helps.

Sean is right. You're gonna' need a LOT of power. Probably more than you may think.

If you're in love with your speakers and don't want to get something that's more efficient, you may also want to consider the Sunfire Signature (600 watts X 2). There is one listed here on the AudiogoN for exactly $2K. I've heard the non-Signature (300wpc) and it was outstanding. Every bit as good as the Bryston and better than the Aragon (IMHO). At more than twice the power of the Bryston, I think it might be a good solution to your dilemma.

That's a HUGE room!!