Will the Outlaw ICBM work for me?

When I balance my 7+1 speakers & sub for 75dB using the noise generator in my receiver (B&K)-- all is well for THX movies.

Then, when I put on my SACD - the sub is about 13dB lower volume than the remaining channels (almost zero bass).

I can fix the SACD by balancing the speakers using the SACD noise generator - but then the THX bass is 13dB too high !!!

I think what I need to do is attenuate the sub output from the Sony SACD by 13dB