Two observations regarding your comment that using an active driven woofer precludes bass performance evaluation of our electronics.
1. I have a set of Dennis Murphy's Philharmonic Three speakers which have awesome bass performance from their big transmission line woofers. No problem with our electronics not having a great passive system to drive. Note that the Philharmonic threes don't really have a "big woofer". They actually are Revelator 8" drivers, one per channel. Its just with the carefully tuned large transmission line cabinet, they play like then have a big woofer, very well controlled, with tons of power and a VERY deep and clean deep bass reach.
2. In an active system in which the bass signal is taken off the speaker feed rather then directly at line level from the preamp, you actually are running two bass amplifiers in series. First the main system power amp, even though it is unloaded at low frequencies, and second the built in woofer plate amp. Obviously the quality of the main system amp will affect the final bass quality of the system as the signal to the bass amp in the woofer section is derived from the system amplifier. At Axpona, we did try the 35W/Ch Ultravalve driving the Exoticas but went with the Fet Valve 600R, even though overkill for power, for two reasons. First, the 600R is even a higher resolution and more transparent amplifier then the Ultravalve (and it is very hard to beat). Second, the low bass response of the 600R is superior as it is not limited by being transformer coupled. The Exoticas sounded lovely driven by the Ultravalve, they sounded exquisite driven by the 600R. Having a main power amp with superior bass performance still is important.
I have suggested to Jim that he provide a line level input for the plate amp but he is concerned this would open a can of worms in trying to get an appropriate seamless match from the top and powered sections of the speakers, and he certainly has that done perfectly as is.
Frank Van Alstine