I suspected that the mains might be running large. The 1070's bass management is doing what it's told.
I had a hard time finding any good info on the Earthquake Saturn Orbital speaker, but I finally found
this . The frequency response is a little sketchy. It has a "bandwidth" listed but doesn't mention what tolerance is used to determine that. The lower limits of 20Hz for the towers, 40Hz for the center, and 30Hz for the monitors make me think they are going more than the typical -3dB to get those figures. I'd suggest trying "small" front speakers and a crossover of either 40Hz or 60Hz.