with any receiver or amplifier, you calibrate all your speakers and subwoofer to the SAME SPL in dB's, and leave it there by using a Radio Shack SPL meter, or the built in test tones and mic that comes with some receivers. You can adjust the gain (volume) of the sub either on the back of the sub, or by using the sub level adjustment in your receiver or integrated amp.
Normally you calibrate everything to 75dB's and leave it there, but some like to have the sub a little hotter (louder), it is your preference.
