In 2009, Sean Olive presented at the AES and published a nice paper called “The Subjective and Objective Evaluation of Room Correction Products” with listening tests comparing 5 products to unequalised response : see here.
It is interesting to see that :
- the best correction was obtained with an average of RTA measurements on a volume of 1 to 2m around listening place (so quite similar to MMM)
- measurement after this best correction shows a continuous slope of about -1.2dB/octave, which is between neutral (-1.4dB/oct) and bright (-1.05dB/oct) targets found on average when you use our automatically calculated target