I just realized I overlooked a simple solution to the whole deal. And it was in my correspondence with Audyssey staff on the -12 level setting.
1) Run Audyssey
2) Go into speaker menu and manual, and then levels
3) Set AVR volume to 0.0 for reference, which should yield 75dB on a SPL meter
4) Find the loudest speaker (say my center is 81db)
5) Adjust all others to 81db
6) Tinker with master volume and test tone to figure what volume is now 75db (should be -6.0 instead of 0.0)
7) Adjust sub channel up 6db
8) Done... Just remember -6 is reference level, not 0.0
