I acquired a Behringer XENYX 1832FX mixer; all works fine. But, I can’t seem to discreetly hook up a sub-woofer to it. This is probably a simple question but, getting it right has eluded me. I have read through the manual several times and, the language just makes my eyes glaze over. It seems geared more to “Recording” approaches than straight “Playback” and “Setup” techniques. The mains sound fine; I can run the subs through the mains and they are receiving signals okay; and, I can run the sub from the main speaker’s output okay. But, I want to be able to control the subs separately. How do I hook up one or two subs? Finding the right sequencing for using the “Subgroup”, the “Control Room” and/or the “Monitor” eludes me. Have I just missed it or, is there a little wrinkle and twist to do to get it right?