I’m in the market for a sub or two
You might start by researching the value of two, or more subwoofers vs. one.
Also, it would be great to see what your system looks like under virtual system. What frequency range should the subs be covering? How big is your room? What are the room dimensions?
Another question that I have is why don’t more manufacturers offer subwoofer DSP? What is the downside of DSP? I can see that the upside might be the ability to place the subwoofer(s) in less than ideal position. Is DSP one of the top features needed when shopping for subwoofers?
I recognize that you simply asked for DSP subwoofer brands/models, but I guess that I’m asking why DSP and is this the best solution for your room/equipment? I went with REL and it did take some work to get things right, but that was a one time effort. One of the main challenges that I had with bass was keeping the stylus/cartridge/tonearm/platter free from the subwoofer output. This issue extends beyond analog play, but can also act upon other components.
Lastly, are you trying to get things right within a two cubic foot listening box, or will you need to consider a larger listening area? This is an important question and one that goes back to subwoofer placement, type and number.