How To Improve B&W N802 Bass Response?

I’m not satisfied with the bass response of my current system in stereo. It seems weak and doesn’t seem to fill the room at low to mid volume. I’m looking for any ideas or suggestions on improving the bass response. My application is mainly 50/50 stereo music / multi-channel HT. Listening room dimension is 24’(W) x 17’(D) x 20’(H) with openings to living room, foyer, kitchen and sun room.

System configuration:
• Digital sources: Sony DVP-NS 755 DVD Player and Scientific Atlanta 8300HD Cable Box
• Digital-Analogue Converter: Apogee Mini DAC (1 week away from being replaced by Apogee Rosetta 200 DAC and Big Ben Clock Regenerator)
• Preamp: McIntosh C200
• Amps: 2 x McIntosh 501 monoblocks
• Speakers: B&W N802
• Cables: Mogami balanced XLR interconnects (soon to be replaced with Apogee Wyde Eye for all interconnects), Cobalt copper speaker cables bi-wired to N802s.
• Receiver: Denon 5803 (for HT only passing thru C200)

I had tried a few configurations along the way, though I’m not satisfied yet, they may be interesting tips for some of you with similar components:
• Canare L-4E6S Star Quad balanced XLR cables tend to “filter” out mid and high frequencies to a point that the sound becomes muddy.
• Belden 1800F XLR balanced cables are better than Canare where they are clearer and seem to give the illusion of sound stage opening.
• Mogami XLR balanced cables better than the above in my system. They are very transparent, clearer and sound stage opens up tremendously.
• Setting the output trim to +12 on C200 makes a lot of difference. It drastically improves details and sound stage even further.
• Connecting N802 low frequency taps to 8ohm and mid/high freq to 4ohm taps of MC502 helps. The bass response seems to be louder and the mid/high seems to be “sweeter” and just right.

I shall soon see what kind of performance improvements from the Apogee XLR cables, Rosetta 200 and Big Ben.

I’m also considering getting a good sub to extend the lower frequency. In my initial research, the SVS PB12 Ultra/2 ($2300) sub seems interesting. It has 1000W BASH digital amp and 2 x 12” TC Sound Ultra drivers. Anybody has any opinion about this sub for music application? I’m wondering how well it blends in with the N802s. I’m not sure how good the 1000W BASH amp is compared to McIntosh MC501 monoblocks. Would I be better off getting passive sub and let the 501’s drive it?

As an alternative to sub, would a 2-channel equalizer help boost the low frequencies of N802s to make frequency spectrum “flatter” at a given db? I hate to waste my investment on N802s, I mean the spec says it can go down to 30Hz. My reservation of EQ is it stretches out my signal path (dtx EQ has AD and AD built-in, in addition to my Apogee DA in the signal path). Not sure if this latency will lead to video syncing problem for HT application. Also, I don’t want to find myself having tinker with EQ’s instead of enjoying the music. If you have good experience with EQ, please share your experience about the brand(s) you tried.

I will appreciate any suggestions you may have on improving the bass response.

Thanks,
John