Recently I discovered that my Yamaha PSR-S950 sounds good with a usual computer speaker system (Microlab Solo-1), even at maximum volume, while my Roland Juno DS sounds distorted if I play loud. That made me thinking that Yamaha's sound is already adjusted to sound well on most devices, but for the same reason it doesn't sound full enough. When I play some piano or EP on Juno DS it usually sounds reach enough, but when I play the same on Yamaha I end up adding a layed and a style just to sound more convincing and eventually I get tired from always playing so many parts.