subwoofer crossover- lowest is best almost always?

That sounds like an interesting component.  

Nah, you just didn’t place the speaker/sub correctly. It’s very hard to do. On some odd rooms it can be  impossible.

Also, make sure you have bass management, and AVR or processor is really what you need, something like Dirac.

Actually, I do know how to set up a system and from my experiences, anything above 30 hz and systems start to sound more like a pa system.  The most important part for me in setting up a system is main speaker placement.  Then, where do I have my components.  Sticking a huge subwoofer in an area close to my other components causes problems.  Ideally, they would be on a side wall but that is a luxury in my view.  Subwoofers are made to reproduce low frequencies, not be a midrange.  If my speakers only go down to 50 hz, I cannot expect miracles.  I will never get the soundof a true full range speaker, but their are compromises there two. Most full range speakers are rather large objects so they need a larger room.  Speakers that go down to only 50 hertz are not made for a large room.  So a sub crossover set at under 30 hertz should give you more than enough low end and integrate fairly well with main speakers down to 50 or 55 hz.  

Actually, I forgot about room acoustics, that is probably the most important part of good sound