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
The phase difference matters ONLY when it is compared to ANOTHER driver in the acoustic vicinity. It does not matter if the speaker is on its own, or it closely matches the OTHER speakers. In the absence of those, or when the sound from anything else is not significant enough with respect to the subwoofer, the phase angle does not matter.

It is all relative basically :-)

i agree that setup flexibility with a subwoofer is of utmost importance the level and phase can be a big factor in proper sound and mesh with the rest of the system as well as placement.
@larry5729, you really should start with level matching your speakers to your subs instead of just turning down the volume where you can barely hear your subs. At least this will give you a much better starting point for where the volume should be. You've spent all this money on subs, and you don't really know if you have them set up correctly. It's a simple process, and you only need a SPL meter and sine wave signal (free on internet).
Ugh, again...stop complicating things, and ditch any and all subs and buy speakers that do bass....subs belong in HT, and that is where they will stay in "my world". Its 2 channel audio, not 2.1.....
I have an advantage in that b&w’s simple set up software allows you to perform all parameters from your listening position. via laptop you can set phase, crossover and gain very quickly by ear. once dialed in it sounds like the main speakers have great bass as you truly can’t locate the sub’s position. without the laptop set up i’ve had as much trouble as everyone else.