"A keyboard of this caliber should have a better quality slap bass."

Layer and or split another bass voice with it, add EQ, add compression ( something ). Factory default voices ( if you dont like them ) are simply a foundation to build your own sounds with. Have to break the keyboard in to MAKE it do what you want it to. Hoping some random sound designer will drop off pleasing tonality that fits your needs out of the box on a mass produced instrument, is hoping against hope.

Hope that dint come off as insulting...as I only wish to express, your new keyboard has more potential then whats on the surface.

"some good hip hop drum beats"

If you want to beef them up even more, use your drum machine as a sound module. You could trigger the drum machine with the psr2000...or trigger the psr2000 with the drum machine. Heck even mix drums from both...

"seems the speakers are very senstive to interference."

Screw them for anything outside of random playing around...just use some headphones, external speakers. Such as whatever you home stereo system is random random random. LOL just dont put your cell phone on the keyboard and you should be fine. Went into a big thing on interference when helping bricks with some recording issues some time back.

Oh...and GRATS on your new board