I use a pair of Yamaha MS-60S...60 watts, powered and using the then new AST speaker design. AST stands for Active Servo Technology and uses a special 2-way speaker design and ported/vented cabinet for very decent bass response even at low levels.

They aren't enormously loud as they are designed as monitor speakers, rather than a small PA, but they do produce a full range and are loud enough for most monitoring situations and were absolutely perfect for my restaurant work.

They are also relatively lightweight (at 25lbs each), extremely reliable, and, at 25 years old, they still work as new, and have never given me any problems. My previous arrangers, and now my Tyros4 sound awesome through them and I have them on tilted monitor stands on either side of the keyboard and slanted up to face me.

When new, they were over $800 each, as they were Yamaha's top-line stage monitors at the time, but they were worth every penny.

I've gone through several arrangers, but because of the MS-60S's excellent quality, I've only needed the one sound system all these years.

If I was to go back to gigging again, likely as one half of a duo with a guitarist/vocalist, I'd invest in a pair of Bose L1's (not the Compacts) as they would likely be a one-time-buy as were the Yamaha MS-60S's.

A performer's PA system is every bit as important as their choice in keyboards.

Ian