hi bevensee
It's not an exact science in my experience. I have run my ER3 stats for many years with a KT88(30-40watts), and found the combo entirely satisfactory. However, I used a WAD 6550 for some months with the same speakers and that was entirely unsatisfactory, I never did like the presentation. I have used SS muscle amps in the past but they never delivered what the KT88 does.....
I can't speak for the exact combination but you're probably on the right side of the risk equation.
speakers here:
http://www.vitalstates.org/diy/elect...trostatics.htm