Hey @navyachts all good here! Hope you’re doing well!
I never felt the need for subs with the ML Montis. I’m surprised to hear your setup is lacking in bass department.
It’s possible you’re sitting in a null. That’s the only thing I can think of.
I would recommend trying to move closer to and then further away from the speakers while playing a test track that is known for good bass. See if you hit a spot where the bass response becomes acceptable. One other thing to try is to move the speakers. Further or closer to the front wall. Make small adjustments 1” at a time. But try the listening position first.