Wow! Thanks guys. I'll try some stuff out later.
To answer some questions (and maybe give me some help):
-> I'm running the sub from the sub-out in the pre-out area of the Denon, set to LFE (not LFE+main).
-> Unfortunately I can't disable the xo in the Denon. Do you suggest therefore that I set the EP-500 to 100hz and try to control with the Denon? Or the other way around? Or will it matter at all.
-> My other system (5.1) has Energy C-5s (front floorstanding) NHT SuperCentre (center) NHT SuperOnes (rear), and a custom 10" downward-firing passive sub driven by a NHT SA-2 amp/xo where the xo is continuously variable from 20 - 120hz. When I move this sub to the Denon system I set the xo to 80hz as well... and all the bass nuances (especially on my jazz stuff with acoustic bass) comes into focus.
-> I've tried the phase switch several times - but by myself. I'll get someone else to flip it tonight.
-> I'm using neither a test disc nor a SPL meter! Just my comparisons when I plug in the other sub... If you can recommend a test disc and a SPL meter please do so! (Thanks!
-> I initially (Jan '06) had a Denon 1920 and the motor noise I found unacceptable. Figuring "what can you expect for $400" I upgraded to the 2910 in March. It had lower motor noise - but wasn't silent at all. So I took it back and in a quiet listening room did back-to-back comparisons with the 2910, the 3910, and an Integra. All had unacceptable transport noise during quiet parts of the music (sitting 10' away). After some research the Cambridge was pointed out to me and it is absolutely silent. I should mention that I have about 40 SACDs / DVD-As as well so needed that feature which restricted my choice somewhat.
I really appreciate the comments, folks!