Ever wondered how much output is being sent to the sub bass? Well, a simple and very useful solution is to buy a relatively affordable audio mixer and use the low pass outputs from the varies outputs from the (left and right combined) as one single monaural output, the same goes for the center channel with a monaural output and lastly the surrounds with a single monaural output all assigned to the mixers inputs.

Next plug the LFE.1 into one of the mixers inputs in all there should be x4 inputs fronts left and right combined, centre, surrounds, and LFE.1.

Now use reset the output levels for the two single sub bass speaker