It's built like a rock. I think you literally could roll it down staris and not hurt it. Case is heavy, stiff plywood. Real tight construction. Carpet covering and metal corner caps.
Knobs are fairly sturdy felling, but they can be pulled off.
But this is pretty normal. I think it was a loose screw somewhere, but I could never find which one, and it eventually went away, so I didn't worry about it. The style of music I like is progressive and classic rock, like Kansas, Queen, Rush, old school Elton John stuff, and Dream Theater. I would give the KC-300 an overall rating of 9 and a half. There are just a few small features that it lacks.