Plugging a Sub into one of my controllers

[Quintessence]

Hello everyone and sorry to bother you this late!

I have a quick (depending on your ability to transcript what I will say) question that has been bugging me for a while.

I own a DDJ-SR and a novation Twitch both connected to my macbook and Serato. (I don't own the actual DDJ-SR yet (stupid amazon is taking forever to ship it)

I work in a bar with speakers connected to a fast track pro (to bypass twitch's awful sound card level) with RCA's. They have a sub that they bring everytime unfortunately my current outputs don't allow me to set it up. Other DJ's with mixers just plug it straight to their mixers with the XLR but I don't have an XLR output on neither my twitch nor my fast track pro nor the DDJ SR i'm about to get.

Is there any way for me to connect the sub to either twitch or the fast track or the DDJ SR when I will be getting it by using maybe an XLR to Rca cable on any of the outputs I have available. (I won't be using the Fast track once I get it as the sound will be controlled by the Pioneer controller and my twitch will just be plugged in USB to have a few controls I won't have on the DDJ).

This probably sounds confusing and I'm sorry in advance but if anyone can help me get this fixed someways, I would be really appreciative.

Thank you in advance!

[Jester]

Booth or Rec out. Thats how i do it.

[Quintessence]

Thank you for the answer. I will use the booth whenever I get the DDJ SR. As for now, would it work if the bar speakers were plugged as RCA to output 1/2 on the Fast Track and the sub to TRS output 1/2 with an XLR to TRS cable?

Thank you.