@northman Nothing to add to DBA concept, particularly for larger rooms, when you want more than a "sweet spot".
I would not discount DSP, though, particularly in a smaller, regular room, and also in particular with speakers minimizing room interaction (like dipoles with cardioid radiation patterns or smaller monitors like the ones you use/intend to use). Underlying arguments have all been made (wave length fitting in a room, spatial cues from higher frequency/shorter wave length spectrum).
After a lot of trying, incl. e.g. Velodyne DD subwoofers with integrated room correction, DSpeaker products have done the trick for me.
You could combine - for a small room - two 12" sealed Rythmiks (
http://www.rythmikaudio.com/L12.html) with a DSpeaker Dualcore (Stereophile Class A recommendation,
http://www.dspeaker.com/en/products/20-dual-core.shtml) from Underwood HiFi, plus a good low-noise power supply from Underwood or iFi, and around $2,000 you would achieve superb low frequency extension with all the qualities you are looking for in your room (and much bigger, more irregular rooms, if desired at a later time).
No association/financial interest. Just a happy listener.
Happy Holidays!