I tried one two weeks ago...it was hooked up to a Hammond XK-1.

The rotary effect sounded very good through it and the K4's "tube" effect was nice.

I got the sales guy to hook it up to a PSR-S900.

It sounded pretty good as well...quite loud...but don't expect much stereo separation, especially if you are used to hearing stereo through a pair of powered speakers.

I don't think the speakers are long throw so it won't really project the highs all that far compared to a PA speaker.

Also, it's quite heavy and rather awkward to carry.

Overall?

Very well made, LOUD, fairly compact, heavy, designed more as a keyboard (electric pianos, synths, organs) stage monitor than a substitute for a PA.

Good luck.

Ian