I've got a two week old PB12-Ultra and it's an amazingly powerful subwoofer. My home theater room is better than 20,000 cubic feet (really high ceilings) and the thing lights it up pretty well. I've got one plug in installed and used the Avila disk and the Radio Shack dB meter to tune the thing to match my current (20 year old Infinity Reference Standards) towers, side and rear surrounds on my Yamaha RX-V2600. The thing will suck the air right out of your lungs - well it does hit 85 dB at about the 10 o'clock position on the amplifier's gain with the receiver set to -6 dB on the THX text tone. I've only watched a few good movies as I was out of town last week - the shoot out bank robbery scene in Heat was amazing as were a couple of the helicopter fly-bys. I got the oak finish and the furniture is very good quality.
I'm waiting on the rumored rear venier finish of the Axiom speaker line to become available before pulling the trigger. Once the new speakers arrive I'll get serious and evaluate the need for a second subwoofer.
The Reference Standards I have have twin 8" woofers in the towers so they can contribute a bunch of base themselves. The Yamaha wants to set the crossover at 60 Hz on them.
