Sorry, but this whole area of filters, cross overs and such is SO new to me (i feel pretty dumb, actually, as I'm finding, if you do some research that Bass is a MUCH more complex issue than just throwing down a boom box in the corner), ie, items from Marchand, Behringer Equalizer, Outlaw Audio's ICBM units, etc.

I just got into high end audio a little less than a yr ago (my bud gave the '
first 'free' injection)

For now i will stick with 2 channel, but will probably buy the Denon 3803 multichannel receiver (7.1 x 110 watts/channel) as I also have a pair of Mission 731pro bookshelf speakers i might use as the rear for HT
(i will probably go that route is a few months).
I just don't want to sacrifice sound from 2 channel, if i go this route.

ROOM DIMENSIONS:
-9 ft ceilings, 13 ft wide x 35 ft** deep
**actually the sofa end the living room at 15 feet but continues back into the kitchen, hence the longer measurement of 35 feet as stated.

MUSIC: 50% music (rock/jazz/blues/some classical), the remainder is HT
I can't play at ear splitting volume levels as I (for now) just rent.

EQUIPMENT:
-Unico INTEGRATED hybrid tube/ss amp (80 watts/2 channel) by Unison Research in Italy (modded by chris johnson of Parts Connexion).
-Sony 999es sacd/dvd player modded by audience av
-Devore Fidelity (ported) Gibbon 8 floor speakers (35-25 hz)
I also have an integrated (older) NAD 710 (20 watts/2 channel)amp/receiver.

Just recently I had Chris (parts connexion) put in 2 full range (l/r) preamp outputs to drive pair of subs (rava or SE edition) in the Unico integrated amp.

will any of the aftermarket accessories work (marchand, icbm, behringer, etc)

I recall Chris Johnson emailing me noting that using a high pass filter in my system is difficult (like the one HSU makes, as I was considering the VTF-3) "Most subs have a low pass....so, a full-range output is fine.....but you have an integrated amp, it's difficult to bandwidth limit the amp...to give it a high-pass filter, really, you need a separate preamp, amp and outboard cross-over then.....".

Basically I want to get the most versatile system for my room and have great bass I can control fully and not kill my speakers, but am confused over if the sub I choose (probably Adire Audio's Rava) will work or not (esp if I go the denon 3803 multichannel receiver route or if i buy some of the aftermarket items/ marchand/outlaw's icbm/behringer bass equalizer.

Any suggestions are MOST appreciated, esp if you can help direct me through this nebulous area.