The short answer is: the ASL's are 200w/ch and the 275 is 100w/ch (and the Perreaux is 200w/ch.)
Since the preamp is driving the Perreaux with the same volts as it's driving either of the tube amps, naturally the bass will sound louder relative to the panels driven by the 275 than driven with the ASL's.
Since the preamp is driving the Perreaux with the same volts as it's driving either of the tube amps, naturally the bass will sound louder relative to the panels driven by the 275 than driven with the ASL's.