Ha ha...well, in my vernacular here in Cape Breton, the expression "it's not bad at all" is usually interpreted as being, or meaning, "good".
I suppose it could be read as "not bad at all" and understood as "not very bad", but "not much else".
However, I liked the sound...it was a tad tubby in low end, but the mids were okay as were the highs...decay a mite short, but very passable.
I have never played a Ketron of any sort...they are Yeti here in my neck of the woods, but I have played lots of Casio as there is a dealer 5 minutes from my home.
I thought Fran's guess was pretty close as well, as I had used Roland Sound Canvas extensively many moons ago...it is close to that sound for sure.
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.