Hoping I can get some discussion on this topic from some of the DIY sub gurus here: One of the biggest obstacles to good integration between main speakers and subs is the implementation of the digital crossover on an HT processor. Most of the receivers and prepros on the market were designed with an electrical high-pass @80Hz, 2nd order, 12dB/octave rolloff bass management algorithms to fit THX certified speakers. If your speakers are anything other than THX certified (not my cup of tea) good crossover integration across the crossover boundary (between those speakers and a sub) is nearly impossible. Great musical sub integration with an HT processor's internal bass management and non-THX speakers is almost an oxymoron. Personally, I prefer a high quality active crossover with symmetrical 24dB/octave L-R high-pass and low-pass filter slopes. There are a number of HT processors that allow more sophisticated bass management than what I mentioned, i.e. Theta, Meridian, Lexicon to name a few. What I'm referring to is the assumption made in the digital bass management algorithms about your speaker's low frequency rolloff characteristics. I find it very hard to blend a speaker with a 18-36dB/octave low frequency rolloff/slope --that many ported speakers have-- plus the 12dB/octave electrical slope of the HT processor for the high-pass side of this crossover equation (equals 30-48dB/octave slope) with the low-pass side of this equation which the HT processor models on a 24dB/octave slope. The anomolies (peaks and dips >3dB) at and around the crossover frequency described above make this setup less than desirable for a smooth main-to-sub blending for the best musical enjoyment. My point is NOT to use a sub's internal crossover, but instead to use an active external standalone crossover (like a Marchand ) to optimize speakers, sub, and room. To do this means re-directing all bass from Small center and Small surrounds to the main Large L&R preouts and re-directing the LFE to the main Large L&R preouts as well. Then the xover is only done once; from the Large L&R preouts to the active external crossover and then to the L&R mains and sub(s). I find this provides the best musical optimization of a sub for 2-channel and still works great for HT. For my speakers, room and sub this happens @60Hz. I've been doing it this way for the last 4 years.