I have added a second sub to my system and I am trying to blend it with my speakers. What should I be listening for exactly as I turn the dial from 0 to 180?

If your first sub is already optimally blended (phase-wise) with your mains, turning the phase knob on your second sub will either increase or decrease the bass output, depending upon what the initial result is, from your listening position.

Hope it shakes the cushions. Careful, now!

I am not even sure if the first one is. I never really understood what it was I was doing with that setting. I guess you are supposed to play it by ear?

Your rig shows an LFM-1 as your first sub (good choice!). Outlaw's got a nice section in the LFM's manual for optimizing the positioning and phase adjustment (although it's only a 180 switch) for 1 or 2 subs. It worked like a charm for mine in my (less than ideal) bedroom space, so I recommend it highly as a first step.

I did switch th LFM to 180 which sounds better . The other sub is an SVS PC Ultra Plus with a little dial that is adjustable from 0 to 180. I wish it was only just a little switch that would be easy