I am not familiar with the Avia disk, but if you have not done so, play through the audio adjustment section of the disk without doing any calibration just to see what instructions they give you. It should tell you whether the reference level you want is 75db or 85db.
I don't know what receiver you have, but check your receiver's manual. Somewhere in there it should tell you what volume setting is "reference," which is where you want the volume to be set when you begin calibration.
WARNING! Reference volume can be very loud. Protect your, and your family's, hearing!
On my Onkyo 797, I have my display set to "Absolute" which displays the volume with a minimum reading of "0," for no sound, and "100" the maximum. As I turn up the volume, the numbers on the display get bigger reading 79, then 80, then 81, then REF (instead of 82), which tells me that the 82 reading is reference.
I have the option of setting my display to "Relative" which displays the volume as a decibel value on a scale which runs from from -81 (db) up to +18 (db) with "0" being the reference point which equals the volume setting of "82" on the "Absolute" display. If this is the way your display reads, look for that "0" setting.
Yes, assuming you have a subwoofer, I'd start with all my speakers set to "small," and everything set at 0 in the receiver menu.
As far as which subwoofer volume knob to use, it's a balancing act. You might start with the knob on the sub set about midway, and the receiver set to "0," and go from there. You don't want to find yourself turning the volume level in the receiver too high or too low, and the same with the knob on the sub itself. The receiver setting doesn't have to be exactly at "0," but if you find your setting it in excess of -6, or +6 to reach reference, then you might want to get a little closer to "0," and compensate with the knob on the sub itself.
Hope this helps some.
