I ended up calibrating my 5.1 setup using a SPL meter. My final results are:
Front left and right - +1dB
Center - +4dB
Rears - +3dB , +4dB.
Fronts left and right and tower speakers so thats why i ended up setting them ''3dB'' lower then my other speakers. Now im a little bit of a bass head. I ended up setting my subwoofer to +3dB. Is it safe for the receiver to bump it ''1dB'' more so i end up having my sub @ ''+4dB''?? Receiver is Onkyo tx SR-308 and every thing is set to small with 80hz for all speakers.
Depends on how loud you play. If you push the system loud I should think, with a positive sub setting, you may get line level clipping on the avr output or the sub input. I started a thread asking whether it's better to turn up the sub's gain knob and aim for a negative sub setting on the avr rather than 0 as usually recommended but nobody responded.