There is an interesting article here:
http://www.soundoctor.com/whitepapers/subs.htm
by Soundoctor that states that modern sealed and active subs like the JL audio subs, have about a 10 ms group delay. That means to get the impulse response of the mains and sub to match, you need to move the sub about 9 feet closer the listening position than the mains. For many of us, that would literally mean sitting on the sub.
The alternative is to delay the mains somehow. Most HT receivers/processors have the ability to do this, but I'm not aware of any "audiophile" preamps with this ability. I owned the Classe CP-800 and I know that although it had some bass management and room correction features, it could not delay mains wrt sub.
Active crossovers like the Bryston and JL's own CR-1 also don't have this capability. Are all audiophiles with subs doing it wrong- or at least sub-optimally?
I found that it can be done in JRiver as described by benchmark:
http://benchmarkmedia.com/blogs/news...1-music-server
but additional dacs and sound cards and using JRiver for volume is clunky to say the least.
This made me seriously reconsider trying to integrate a sub.
Thoughts?