Update 1: sub is plugged in via the 100hz rca pre-out. I ended up lowering the crossover frequency to about 90hz against my own recommendation. I did have a slight phase issue, but I also have a phase switch for that.

Verdict:
Worked fucking great on Yes, Fragile. Worked less great on Led Zeppelin IV.

I'm not sure it's worth the money. But Fragile on vinyl is kicking right now. Really sounds great.