One guy over on AVS said he heard both the 500 and the 600, said the the 500 is 90-95% "the bass" of the 600...That is coiming from a guy, that has been through 10+ subs..That's what iced the deal for me. Last night I cal'd the speakers at 80 dB, the Ep500 at 85 dB. The sub gain is at like 25% of 100% scale, like 5- o'clock position. When I moved into the 7Pm range, that side of the house was going into resonance!! I have 12 ft celings, 3,000 cu ft room, with complete openings bioth sides, leading into another 3-,4000 cu ft areas. One EP500 engulfs all of that with bass! Dual set-up would be quite scary!

Vince