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
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. 

"However, at times some can respond rudely. I think if they avoided the put downs it would allow people like myself to know how to ask the right questions without being criticized."

You would have better odds at getting Pelosi, Schumer, McConnell, Trump, and AOC to choose between water or Ice Tea for a lunch meeting....

@newtoncr - you are correct, measurements should be from listening position, thanks for mentioning this. Also, I should have mentioned, the subs and main speakers should be level matched first.

@audioguy85 - I get it, there's some guy's that don't think subs belong in an audio system. I can respect that. However, adding subs isn't just about hearing sub bass, with multiple subs, and careful setup, you can get a much better distributed frequency response in the bass region without using an equalizer, or DSP. 
My sub has continuous level crossover and phase adjustments. It is right next to my listening position so very easy to adjust properly. Phase matters the least of the three but still matters and makes a subtle difference on the sound. Granted it is not easy to get tuned in in many cases especially where sub cannot be adjusted from listening position.
The more subs the more randomized the wave patterns are in the room which is a good thing and playing with phase an exercise in diminishing returns.
Funny to me how everything is a black or white issue. Phase either matters always or not at all.   Even fuses:  same deal. Yardda yadda yadda. I know. I know. Thinking is hard. Sometimes I try to think but nothing happens.

Level matching and setting the Phase are the simplest, providing your subs have the functionality. It's everything else that makes it more difficult in my experience. Room placement, selecting the correct crossover(s), and loudness (within the parameters of level matching) become much more harder when you start taking measurements. I tried adding a third sub the other day, and after spending 4 hours of trying to improve my frequency response, I was only able to match, never improve it (most times it was worse). So, I disagree, adding multiple subs and selecting what ever crossover sounds good doesn't mean it's better, you'll only know that if you take measurements. So not so black in white.