Guy, the object of calibration is to be balance the volume levels of all speakers. Since the mains, center, and surrounds are different speakers, at varying distances from the listening area, the settings you make in the receiver compensate for these differences. Once calibrated that balance works for both HT and music.
And, remember. Those settings are not etched in stone. Many of us bump the subwoofer from 2 to 5 dB for movies, and back it off for music. Likewise, many of us bump the center channel a few dB to increase dialog intelligibility with movies. The calibrated settings are a starting point, and may serve you well. But, don't be afraid to experiment a little to see if you prefer a few dB one way or the other .
