I was told that if I were to use a non-THX sub that whenever I decrease the volume below reference (0 db), which is quite possibly quite often, that the only way to adjust the output of the subwoofer is to use the sub's volume knob on the sub itself, as oppose to using a THX sub, in which case when one lowers the overall volume on the pre/pro or receiver, the THX sub's volume decreases accordingly. I am wondering if this is indeed true or is it untrue and based on THX marketing hype? i thought that using any sub with a pre/pro/receiver would allow for proper volume adjustment (including adjusting the sub's volume) whenever one were to decrease the master volume on the pre/pro/receiver. however, since i was told otherwise, that unless it is a THX sub, adjusting the volume down on the pre/pro/receiver would simply lower the volume of everything EXCEPT the output volume of the subwoofer, so it woun't work properly unless were to be willing/able to reduce the sub's volume appropriately by actually going to the sub itself and adjusting the output volume knob each time one were to go below reference (0 db). am i totally confused? don't understand this bass management part for 5.1 systems on THX vs no THX. Thanks.