MBox Pro 3 Outputs not working

[xkleenexk]

Alright so I've been through the manual and googled around a bunch, I've had my Mbox Pro 3 for about a year and am just getting around to trying to play a mix using it. I have a Behringer DDM4000, some external effects like the OTO biscuit, and the filters on my slim phattys and minitaur.

I cannot for the LIFE of me figure out how to get outputs 3/4 and 5/6 working. The manual says I can toggle between them for different pairs of studio monitors but thats not what I want to use it for. Ideally I'd like to route sound of them in Ableton to the Behringer so I can mix a live set, or send audio out of them and through a Moog filter or bitcrusher and back in to the input to record. As of right now, I can use the inserts to effect the inputs, but I can't use my talkbox or send a drum loop out through an output through the bitcrusher.

Am I missing something here? The manual says plugging anything in to outputs 1-6 that has an analog input should work. I was concerned this might mean the Behringer won't work since it has RCA which are digital, but I see no reason why my talkbox or bitcrusher shouldn't work, both have 1/4 inputs on them. I've tried fiddling with the settings but none of them seem to work. Do these extra outputs only work if I route them in pro-tools or some BS? I thought it would be as easy as plug-n-play