markv,
This is still an on-going process, where I'm trying to find the optimal setup given my existing physical listening conditions. One of the added variables is the wide difference in recorded source quality. I could honestly say, though, that right now, in general, everything I play in my system sounds great.
Bass (and all frequencies in general) is tricky when you don't have a symmetrical back wall working with the speakers. For example, my left channel is against a hallway, and not close to a corner. The right channel has a perpendicular back wall and therefore I find myself increasing the volume on my left channel to compensate. This adjustment helps all frequency ranges.
The bass in the DM945's is good, but not too deep. I think the SUB is required for frequencies lower than 60 Hz or so. I also had to replace the ramps, initially on top of a common furniture table, with monitor stands, so I could bring the speakers more into the listening room. The difference, as I reported earlier, is very significant, both in bass quality as well as soundstage and an airy presentation. The DM945's need enough space around them to work their magic.
The ramps should work well with enough distance from adjacent walls and de-coupled from the amp and dac (both conditions physically impossible to satisfy in my case). In particular, removing the speakers from the common furniture table eliminated damaging vibrations through amp and dac.
Regarding the ramps, I don't have pictures nor would I know how to upload them in this forum, but these are pretty simple:
9" wide x 10" deep, with heights of 2" on one end and 1" on the opposite end. This particular slope works well with my target sweetspot and the 18" height on my furniture table. The slope may increase or decrease according to your sweetspot's distance from the ramps. The idea is to have an imaginary straight line going from the tweeters to your ears as you sit in the sweetspot.
Now that I'm using the stands, I would strongly recommend these as a first option. The ramps are great if you cannot bring the speakers into the listening room (as was my case until I decided to physically set the stands and speakers at every listening session), and there's plenty of space around them.
I recently discovered that the ideal distance between speakers, in my case, is between 7.5 and 8 ft. I used to have them 9 to 9.5 ft apart, but the soundstage was not as good.
There, that's about all I have learned from the DM945's so far, but all this time I've had one hell of a good time listening to gorgeous music, which seems to improve gradually all the time

There are more avenues pending, mind you, already considered to further fine-tune the gear, this is only sort of the first stage.