It would be awesome to have bass kits to pair with the drum kits.
This is probably a great suggestion for future releases, but as actual drum sound samples quality is pretty high paired with there are several samples used per each MIDI note to enhance overall BeatBuddy sound quality, there is a limitation on how many actual sounds could be stored in memory at once.
While it is definitely possible to reduce overall BeatBuddy beats sound quality to enable playing several tracks simultaneously (drums + actual bass), this wasn’t the initial goal. BeatBuddy is first and foremost a musical tool to play drums. And it does it excellent! Wanting it to play bass track is like wanting it to act as a distortion pedal - definitely cool, but out of initial target scope.
Having all this said, I personally want BeatBuddy to be able to do exactly what you want. A completely functional MIDI player. I hope I will be able to get it done.
We will look into this for future updates.