Which subwoofer?

Audiorusty may be on to something,  while I am in a similar situation as you, my Acoustat  Spectra 33 panels are a bit larger than your ML's , push out a bit more bass. The sub that came with the 33's is Crap. When listening to a bass heavy track,  those panels go down low, then I listen to something with a flatter curve and want more bottom. I have not pulled the trigger but I've been looking at the Schitt Loki Mini + . I've tried to be a Purest,  but with panel speakers and not so good recordings, sometimes you may need just a bit more. For $150 , I would look at this first before spending many times that amount looking for a good ServoSubs x 2...