Hi, I just recently brought a digital Radioshack SPL meter and have managed to calibrate (or try to) my speaker levels so that all 5 speakers are at 75dB. Setting each speaker level to 75dB seems to be straight foward - place the SPL meter at where the ear-level would be and point the SPL's microphone at the direction of each speaker. However, when it comes down to setting my subwoofer level to 75dB, even by lowering the subwoofer level from my amp by -15dB, I can't seem to get the sub's level at 75dB - its always well over 75dB. Am I doing something wrong? Or is the optimal (recommended) subwoofer level above 75dB. Please Advise. PS There seems to be this option which allows you to choose 2 different 'Weighting' option: A - weighting picks up frequencies from 500-to-10,000 Hz range. C - weighting picks up frequencies from 32-to-10,000 Hz range. Which one should I choose?