Just want to be clear about turn the volume up...is this the master volume or the individual speaker volume....? The thing is, once I run the test tone, and if I wish to adjust the volume, the volume that I am adjusting is not the master volume but the speaker volume....and as I run the test tone, the volume for that speaker is already started at ref volume 0 db. That;s why I am a littel confuse, specially when setting the SPL first to 70db (or putting the SPL needle to the center (0)) before calibrating to 75db. any thought???/