The short answer is yes, you can connect a mixtrack pro to an external mixer with post fader effects. I'll do this occasionally with my T1 and Zero 4.
Maybe a better solution however would be a set up like Denon's DN-SC6000 and a DN-X600. Although more expensive than a mixtrack/external mixer (depending on the mixer), you only really need to buy one sc6k, as the controls are layered, and the x600 can be had for 5-600 bucks.
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