I'm using the DeHavilland GM70 (50 W SET) and they have plenty of power for my room (about 14x32x8 feet). I have not tried other amps, so I'm also curious if something like the BAT might work better (there was some discussion on another thread about the theory of using SET amps with a multi-driver speaker - some argued that it makes more sense to use SET amps with single driver speakers). I'm very happy with the GM70 and yet also very curious if it could be improved upon with different amps.
