Andrew,
i got 2 subs: one PC12 Plus (Bash) and
one PC13 Ultra (Sledge) connected through a "Y" adapter at the AVR.

Levels: 12 Plus: 10 o'clock
13U: -12 dB.
The 13 Ultra is calibrated to output about 5 dB higher SPL than
the 12 Plus for the same signal input.

The 12 Plus is tuned to 16 Hz
The 13 Ultra is tuned to 10 Hz (2 ports plugged and HPF filter set at "sealed").

phase: 12 Plus: 0
13 Ultra: 180

Connection: RCA

AVR: Marantz SR5005

Speakers: M80
Xover: 64-80: can't decide which is best...

Trim levels:
M80: L: -3
R: -2.5
Subs: -6.5 (run 3 dB hot)

I haven't even looked to see if there are triggers anywhere in my system...