Mcintosh Equalization

Since you're considering McIntosh level of quality/cost, why not run an experiment with a cheaper option to see if it sends you in the right direction?

Pick up a Schitt Loki for $150, try it out, and if it has either positive or negative results, sell it for $100. You're out $50, but it's a lot cheaper than regretting a 4 figure purchase. If it offers positive results you can seek an eq more befitting of your system.

"Audiophiles" use all sorts of tone controls and eqs, they just call them power cables, interconnects, and tubes. 

Pull speakers out for serious listening and push them back afterwards.  That’s what I did when I had space restrictions, and it costs nothing.  There are products from Herbies, etc. that make it easy to slide speakers while improving isolation.  

As a general rule eq's do more harm than good,its most likely your bass heavy situation is due to poor speaker placement as well as room conditions that only add to your bloated bass situation,heres my thoughts,when people attempt to make a hifi system fit in with their living areas decor,instead of using the rooms decorations to bring the best out of a system,no amount of eq will correct the problems,put some bass traps in the rooms rear corners and add accoustical panels directly behind the speakers and you will see an instant drop in bass bloat,or purchase a Mcintosh preamp with tone controls and simply turn the bass down ,even with room treatments all 3 models of my Mcintosh line arrays prefer to be ran in the -9 to -12 db bass range.

As for Mac EQ's, Geneis writes of the 107, which I have no knowledge of, but I own a pair of Mac speakers, the Ml's and with them have a MQ101 Mac eq. It was made SPECIFICALLY for Ml's and can cause distortion in other speakers. This is written in the manual, so my point is, you should check this out before you buy any Mac EQ.

If you're refering to the MQ 107 or other MQ reries EQ's, they work well to control the bass irregularities. Problem is that you need a Mcintosh AA2 spectrum analyzer to tune the EQ. Hope it helps.