I just noticed that with my HSU sub I only had to turn the gain to about 1/4 of the way up so was a little surprised that on the EP500 I had to turn it up almost half way, I would say it was set at about 11 o'clock compared to about 7 o'clock for the HSU.......
Amps have different gain levels internally by manufacturer so the fact that the control is set differently than your Hsu makes no difference, so long as output SPL is the same. Axiom used to have a very sensitive control and it used to be set at about 1/4 instead of the nearly 1/2 on the dial it takes now, makes fine tuning a little easier IMO.
