Just the TD-50 brain. I’m not much of a drummer, so playing a Zendrum lets me use 8-10 “sticks” to make up for my poor hand-foot coordination. The Zendrum’s whole thing is to allow highly sensitive dynamics over the full MIDI velocity range. John Emrich’s demos go far beyond what most people do with it, except maybe for this guy.
No, I haven’t tried triggering the blackbox via MIDI. To shine, the Zendrum needs a fully multi-sampled kit (like BFD) or the TD-50 to get the feel of real drumming with dynamic variation.