You can still use Impact XT. What you want to do is create a Multi Instrument that contains three instances of Impact XT. Each instance can have 16 individual outputs, so you get 48 total outputs. It will obviously take some work setting it up, assigning MIDI notes to each of the pads, and configuring the outputs, but once it's configured you can save the Multi Instrument and recall it whenever you want.
Start by dragging Impact XT into an instrument track, then drag a second Impact XT to the same track then choose combine, then drag a third Impact XT to the same track then choose combine. You should have something that looks like this:
You can set colors for each of the Impact XT instances so that it is easy to tell which channels in the console are associated with which Impact XT instance.