Alot of midi devices have an in and out.
For instance.
My drummer has a Roland e-drum kit, it has midi in and midi out.
You only need to use the midi out on the drum kit into the midi in on the interface for it to record. But if you connect the midi out of the interface to the midi in on the kit, you can set timings from the interface. (other wise recording can be a bit unstable, as we found out)
The midi jacks are for recording midi instruments is what im basically trying to say
