But that’s not a problem, because then you wouldn’t create 512 steps in the first place, right? 
I was just saying that it is technically possible, and this feature must be flexible enough to cover it.
Isn’t that more complicated? How do you select a sample from the pool via MIDI? And how do you assign that sample to a step via MIDI?
You mentioned the Digitakt and the Roland MC-707. If you have drum machines in mind, we could add the MPC One, the Maschine… I might be mistaken, but don’t they all work this way, select a track / pad via MIDI channel and then play the same sound that you would get if you would press that pad with your finger?
I’m sorry if I keep asking. I’m just trying to help presenting a clear feature request.