I don’t honestly know, but I can tell you this. I am practicing using Ableton as a loop sampler while having it MIDI synced to Traktor, and basically the sound flows something like this
Traktor > Ableton > Soundcard (I use a NI Audio 2 right now, about to upgrade) > 20 band Analogue EQ > Speakers
So maybe you could do a MIDI sync as well and just run all sound out of your S4