I have two infinite baffle manifolds - one in the front left corner and one in the front right corner of my room. Each manifold has 4 Acoustic Elegance IB15 woofers. With the IB manifolds and the 215RT's, I have 14 15" woofers!
When I got the 215RT's, I disconnected my IB system and have been routing all bass to the LCR. I use JRiver Media Center to copy the LFE channel to the LCR. Output the LFE channel from 3 separate channels results in a 9.54 dB gain of the LFE channel which is very close to the 10 dB requirement. Adding .46 dB to the LFE prior to adding to each channel results in a 10.002 dB overall gain for the LFE channel.
Tonight or tomorrow I'm reconnecting the IB system because I have someone coming over tomorrow afternoon for a demo. With the IB system in place, I'll only send the LFE to the IB system and send redirected bass from surrounds to the mains. I'll be able to switch back and forth for comparison.
For two channel, I can do three things with just the 215RT's:
- Play regular stereo
- Copy the bass from L/R to the center with the copied bass from each channel attenuated 6 dB (each speaker outputs same SPL)
- Put a 80 Hz high pass on L/R , combine bass from L/R, attenuate by 3.5 dB, route bass back to LCR
I think 1 or 2 are the best options. 2 sounds a little weightier since you are getting a 3.54 dB gain in the bass.
The bass from the 215RT's and the infinite baffle system sound very close. I really haven't spent any time switching back and forth, though. I wanted to really do some extended listing with the 215RT's before using the IB system again. I listen almost every night, but like to spend weeks (months?) with the same system before starting to compare.