The gain setting would actually depend on the AVR/processor subwoofer level setting, which controls the voltage sent to the subwoofer. Typically we like to see the sub level set at 0 or less, preferably in the -2 to -8 range on most AVR units. This keeps from over driving the sub amp. We do recommend 12 o'clock as the initial Gain setting for calibrating the sub, then adjust as necessary. After calibration setup, I normally recommend turning the gain up on the sub before increasing the sub level in the AVR, unless the sub level is at -10 to -15 in the AVR, then turn it up to about -6 to -8 and if more volume is needed from the sub, use the gain control on the sub itself. Again, this is all highly dependent on the AVR brand, as well as the age of the AVR.