What is the appropriate horsepower (wattage) for a new pair of PSB T2's?

Technically speaking, horsepower affects top speed volume while torque has more of an effect on acceleration. This is why even a lot of solid state horsepower seems less powerful than a smaller amount of tube torque. The greater tube torque accelerates the voice coil zero to 60 much faster. Remember all the world's top speed tests where horsepower rules are run by professionals on a test track. In the real world where hardly anyone has a test pressing and no one has a mastering studio its mostly listening at normal volumes in normal rooms. Where torque is more important than horsepower.

So again I ask, why do you think horsepower matters?

Interesting question. Why do you think it matters?