I'm not stuck on specs, I'm an EE.
Guys, I'm not saying you can't run the 10t's on 40-50 watts. What I'm saying is that these speakers have a nominal impedance of 4 ohm, which means they can drop really, really low under the right conditions. You do run the risk of clipping low powered, and even some higher powered, amps. More specifically, these speakers need a high current amp. User beware. I know several dealers that will not even attempt to run the 10t's on tubes. I wouldn't go that far, expecially considering some of the big tube amps that are available. If you listen at low to moderate volumes you probably will be just fine.
As for performance, 500 watts is no guarantee of great sound, I agree. The quality of power is what matters with the 10t's. This is especially true with bass response as Holenneck posted before. My experiences with the 10t's lead me to believe that the more quality power you give them, the better they respond.
Best to all and enjoy those 10t's!
Dan