The best PA I ever used was a pair of Bose L1 (not the Compacts) in stereo.
Pricey? You bet! But, you may go through a number of keyboards, but you only need to buy the right PA system once.
Plus, using the Bose eliminates the need for a monitor system, which is another added expense and another thing to set up and adjust.
Having the two Bose also acts as a back-up...if one ever fails, you can squeak by with one of them.
If I was to start gigging again, that's the system I would get...a fine (and one time) investment in my opinion.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.