I just wanted to touch briefly on the subject of the aux fed sub. I go back and forth about it with my business partner. I tried it once and will never go back. He tried it a couple times and was all "meh" about it and says high pass filters are enough. The difference may be just that his digital loudspeaker management box has two ins and mine has three so it's a lot easier for me to implement. But here are the reasons I like it.
First, it's much more effective at removing un-needed lows from the program. Sure a low pass filter on every channel will do it, but you have to set every one. It's a lot easier if you're only sending half a dozen channels to the subs instead of trying to keep the other eighteen out of them.
Second, it gives you better control over the lows. If you have the kick drum and a bass guitar in a standard stereo mix, you can control how much lows you get from each one with the EQ and that's it. Feeding them to the subs with an aux send lets you account for that fridge cabinet the bass player brought. It also allows you to be a little more subtle with inputs like synths or playback, you've got a knob right there for low end content.
It's a pretty short subject but one that's open for debate. Hit the comments section and let us know what your thoughts are.