Hi! I too have just installed a new BIC and am having similar problems getting the initial setting anywhere close to 75db. Got it to 85 once but the result is virtually no output from the sub. Have you solved this yet? What are your sub settings? Mine: gain just below 2 (roughly 7 O'Clock), auto, 0 phase, DD, cross-over at max, connected by LFE. Audyssey produces -6.5 but even raising AVR to +3 yields almost no detectable output from sub. To get output I must raise the sub gain to about 9 O'Clock which produces about 95db on setup and drives Audyssey's setting to -12.
My speaker crossover settings are:
R/L at 80 (Mirage OMD-15s)
C at 40 (Mirage OMDC1)
RW/LW & Surrounds at 100 (Mirage NanoSats)
I've tried raising the center to 80 but the result is a less full center with no detectable difference at sub.