07-04-08: GrannyringNow there's an SLA-4, which is 100w/channel x 4, so you could bi-amp at 100 watts per wire. These go for about $439. The really attractive thing about the SLA-4 mated to an electrostat is that the SLA-4 is rated to 2 ohms.
Buy two Applied Audio Research SLA 2 amps. They cost $250 new each. One would also be enough.
I think the funky and low loads that electrostatics sometimes present may be part of your problem.