I've said this before................It used to be that if a keyboard had onboard speakers it was considered a toy, certainly not a pro type instrument. Having a PSR2000 its onboard speakers are the best onboard speakers I have heard on ANY Yamaha board. I heard that Yamaha started using a 12 volt automotive type sound system (which might explain the 16 volt adapter) the last few years so they can use some common 12 volt top of the line audio processor chips like high end car systems use.