Does anyone know of a program that is midi mappable and lets you control multiple channels of audio? (not talking about Traktor or similar software)

I want to use Traktor in external mixing mode so I can send the audio to Ableton (using JackRouter or Soundflower) and use different effects on different channels. When I do this I can map my 4trak to control the volume faders in Ableton. However, one of the faders sends the same signal as one of the rotaries on my APC40.

What I need is another piece of software that I can use to send the audio from Ableton and map the faders of my 4trak to. I know I can use the faders on the APC40 but that isn't always easy when you are doing things quickly (much more convenient to use the faders on the 4trak when mixing). Basically this should take the 4 channels of audio and combine them into two for the outputs on the 4trak. I hope this makes sense.

I might be trying to make this more complicated than it is. If anyone could give me some advice I would greatly appreciate it.