Perhaps this is just obvious to everyone, but it's something I do with my own system, and so I'll talk about it here.
I may be way off base (my attempt at a pun), so all the smart people are invited to correct my delusion.
Here's the thing:
For those people who enjoy their bass levels much higher than their mains, they might want to consider reducing their crossover frequency.
The result in my system is a cleaner sound.
I think its easier to explain the point I wish to make with graphs, so follow along below.
Directly below is a graph of a set of mains (in blue) and a subwoofer (in blue) crossed at 80Hz and the resulting signal in red.
You'll note this lucky guy has perfect speakers and a perfect room.
Crossed at 80Hz
Flat bass 80 Hz crossover.jpg
Another guy has a very capable set of mains and so decides to cross at 60Hz instead of 80Hz. His graph is seen below.
Not much difference in the resulting signal though, except perhaps he gets a bit more stereo soundstage.
Keep in mind he has perfect speakers and a perfect room, so he didn't have to worry about the rooms effect on the mains response at a lower crossover.
Again we see the mains response in blue and the subwoofer response in blue, both crossed at 60Hz....
Crossed at 60Hz
Flat bass 60 Hz crossover.jpg
The first guy who crosses at 80Hz decides he'd like more bass and so decides to get crazy and turn up his subwoofer 15dB.
Below shows what happens to the resulting signal. The bass starts to result in a increased level at about 120Hz - the graph shows why.
This first guy finds his bass too overpowering in the mid and upper bass regions.
Crossed at 80Hz
HOT bass 80 Hz crossover.jpg
The second guy turns his bass up 15dB and finds it sounds just right because the increased bass doesn't start to even rise above the mains level until about 85Hz - the graph shows why.
Crossed at 60Hz
HOT bass 60 Hz crossover.jpg
Anyway, this is just something I noticed on my system and is a consideration if you decide you want that extra bass, you may want to decrease your crossover frequency.
brucek