Well, if you're happy, then you needn't change...stick with what you have....save yourself some considerable loot.

I didn't like the way the Yamaha sounded in mono...thin and one dimensional, comes to mind.

They sound the same way if I play through one of my powered monitors.

I certainly have no regrets getting the two Bose, and perhaps, if you try your PA1XPro through a pair of Bose L1, or whatever kind you choose, then you might find the difference substantial enough to invest, like I did....if not, no big deal, as long as you are content with your present sound.

A nice by-product of using two speakers of any kind, is if one happens to fail for whatever reason, you still have one as a backup...not going to sound quite the same (but having one Bose still maintains great coverage), but certainly better than not having any.

Ian