Critical subwoofer tip


I assume that everyone already knows the importance of phase matching a sub to the main speakers but it’s a little more complicated than simple 90 degrees or 180. The B&W sub that I have has four choices. In every case there has been a definite correct position that can be non standard. My current setup shined at 270 degrees vs the std positions. It’s completely obvious and the other choices would not have been satisfying. 
From my lengthy experience I would want a subwoofer with several phase choices. I personally don’t see how one could seamlessly integrate the mains and the sub without this flexibility. No one asked but i thought this info might be useful to anyone purchasing a subwoofer. YMMV
4425
phase cohesion is of course important. you want to make sure that the sound from the subs arrives at your ears at the same time as the rest of the music. You will need to adjust the phase to within less than a degree if you want perfect time coherence.

You dont need 5 subs in a small room. One is enough. More subs will take up more space and use more energy. Most of the bass will end up  cancelling the other subs. 

Smaller subs are faster as they have less mass. So they can accelerate more quickly. 

Cheaper subs are made of mdf but if you want the best, concrete cabinets are a must.

The best subs will start and stop instantly. The worst ones will ring like a bell long after the signal stops. 

perfect subs will give you clean bass everywhere not just in the sweet spot. 
Clearly in my 1 sub system phase matters not. Drove myself nuts trying to find the right phase, realized that it didn't matter. One man's opinion. 
The OP reminds me why I have completely given up trying to help people get good bass in a room.  Subs are hard to configure.  Get a preamp or receiver with ARC if you get a sub.

Best,

E