I have two of them, both volumes are about as low as I could get sound out of them, about 6:00. My amp is at -5db for the subs and about 0 to +1.5 db for the other channels.
As Peter said, the controls are a little sensitive, it's a fine line between too much and too little (where the sub cuts off).
I have my front wall sub at half and the rear at flat. These aren't meant for volume control in general, but a frequency boost at 35 Hz to compensate for nulls in smaller rooms. Leave them at flat for the levels calibration.
