I didn't get my answers properly highlighted so I'm giving it another shot as well as fixing a couple of mistakes from my original post:
What Axiom subwoofer(s) do you own?
Where do you have the Level, Frequency, Phase, and Subsonic Filter (if applicable) controls set?
Level 7/10, Frequency about 120 Hz, Phase Normal - This sub has no Subsonic Filter and likely produces no significant output below 20 Hz
How are you connecting your signal source to the subwoofer (RCA/XLR/High Level)?
What receiver/processor/pre-amp/integrated amplifier are you using?
What are you using for your main speakers?
LFRs and VP180
Where do you have the crossover frequency and trim levels set in your processor/receiver for your main speakers and your Axiom subwoofer?
THX (80 Hz) but with fronts (L/C/R) set to Large
Are you using the trigger on your subwoofer?
Yes it has an automatic trigger that turns it on when a signal is detected on the RCA. This is set at "Low"