there are so many ways to dial in bass DSP should be the final step. Can you post a picture of your room on the virtual system page? If I were going to give you a generic plan it would be:
1) Get 2 subs and follow Earl Geddes recommendations for placement.
2) Stack bass traps from floor to ceiling in the corners of your front wall.
3) Place absorption on the back wall behind the MLP so the bass doesn’t bounce off the back wall and slap echo.
4) If you still have issues try the 8033 sub optimizer from DSPeaker or the Flex Mini DSP if you are so inclined. I think the 8033 is easier to setup and less of a learning curve but they both work.
You can see geddes guidelines and pics of the room treatments on my systems page, hope that helps.