Get one of these:
Sober's snobby sum-up:
Mic'ing built-in speakers on almost anything is bad, using the midi patches on your SB16 board is worse. From my brief read of your posts, you haven't clearly defined what you really want.
In your original post, it sounds like you want something like a
nord. Small, and they sound awesome. They start around $1,000.
How much do you want to spend? With keyboards, you absolutely get what you pay for. If you want to spend <$100, you're better off getting a dinky controller and pirating some decent softsynths. Also, no decent keyboard has speakers built in. If you see speakers on someone's board, they have a shitty board. I'm rambling.
Refine your search terms, and we'll be able to help you better.