The best way to test out a new keyboard is to use your own speakers if you can. Otherwise going through a stores speakers could make it sound better or worse. Testing out an instrument with headphones might be ok, but I would never use headphones to pick out an instrument and make a buying decision. (Try setting up for example an external style on headphones. You can get it sounding good on headphones and even compare it with onboard styles and they sound like a good match. You take it and use the same style and play it through your speakers, live without trying it out first with speakers and you are likely going to be surprized that the style is not set right for your speakers compared to onboard styles. You'd never know what it will sound like until you use your speakers.