I just wanted to make sure you were aware that the Emotive XPA-5 is on sale for $709 with 5 year transferable warranty and shipping included.
As a minimum, I would use that as a reference for evaluating any used deals.
While the VA's are hard speakers to drive, the standard content fed to the rear speakers are such that you would be fine using a decent 5 channel receiver (assuming that is what you have for a pre) just for those two channels, then buy a 3 channel amp for the center and mains.