I ran my Towers when I was using them as my mains with a 50WPC NAD C320Bee amp. I could run the amp right up to just short of max volume before it started clipping. I mean shake pictures off the walls, literally!!! When SS amps clip you will definitely know it. I also listened to the Towers with a little 0.75W 12B4 SET amp. They would get surprisingly loud with only 3/4 of a watt to work with, much louder than I typically listen to in fact. Also, besides the decent sensitivity of the Towers, their simple crossover is very friendly to flea powered amps.
I've not listened to any of Jack's music, but if it's like most recorded material on CD nowadays, it's compressed within an inch of it's life and tends to sound really bad once the volume goes up. Too much of everything in the mix at the same level.