I have officialy graduated to multi channel thanks to ALL Outlaws.

Many things are new to me so thanks for patience and any help.

Channel calibration, trying to understand the importance and best way to conduct. Is 0db ever used? two channel? I left at 0 for all, fronts seemed quiet, very little from my surrounds, and almost non-existent sub. Set volume with no source to 0db to attempt test tone etc..however felt like it was going to be WAY too loud, even at -10db, so have fooled around at high 20's. Appears the calibration is to keep volume levels even between all 5 channels?
I feel stereo mode sends no signal to sub, is there a 2.1 mode?
Yes have completed speaker config, small, system config, correct distances.