I am using an Acme b2 with a TH500. I absolutely love it. I've had the Acme for a few years now and never really, really liked it with my other amps (iAmp500 or Acoustic Image). I did like it with my GK1001RB-II.
Well, recently I pulled it out of the pile of cabs, dusted it off and plugged in the TH500. A very nice combination.
My B2 is 4 ohms so if I want to get another one, I'll either have to buy another TH500 or run the current one out to a power amp.