I have the Avia DVD for calibrating home theatre setup. I understand how to calibrate my home theatre. However the Avia has two sets of tones you can use to calibrate your speaker levels. The first set is in section 6.2 - Playing at Calibrated Sound Levels. This seems to be your standard tone. It plays through each of the 5 channels. However, it doesn't play all channels at once, to adjust maximum sound level. The second set of tones is in section 7.5 - Reference Tones. These tones are a far wider spectrum, they play in each of the channels and then all at once. Each section says you can use the tones to set speaker levels. However, each one results in a different sound from the theatre. I was setting my levels with the wider spectrum signals in section 7. Recently I got some new furniture in my theatre and decided to recalibrate. I used the tones in section 6. The difference was AMAZING! Using those tones I actually had to turn down my center, front right and both surrounds. But it actually sounds louder at the same volume level, than with the wide spectrum sound. Why would that be?