mpd has "midi out" so you can connect sp and mpd with a midi-cable. Now you can trigger samples in SP by hitting the pads in MPD. The main advantage of it is that you get velocity sensitive pads, plus they are much easier to play with. In addition, when you record your pattern in sp, and you trigger samples with mpd, the sp's pattern sequencer recognize the velocity too. So you can have loud and silent hi-hats whenever you want, no need to creating two hihats of different volume in sp. Plus, with mpd youve got 16 pads, so if youre much into "BoonDoc" shit, you can do it with sp now.
Unfortunately you cannot trigger your patterns with external controller. It's for samples only. The other drawback is that you cannot assign the knobs for effects. As for the transport buttons - Im not sure about them
What is good fam? Appreciate you checking my beat tape. I was wondering how exactly my MPD would work plugging into the "midi in" on the SP? You have intrigued me with this possibility and I wish to learn it.