Hi Chris, this is like when Paul McGowan answers one of my crazy questions - I feel like I’m in the presence of royalty!
To anawer your DSP room correction question, I used a really easy to follow and affordable system from Focus Fidelity. But there is no follow-up testing to “verify” that the filters are doing their job. Focus Fidelity creates filters that plug into Roon and other audio software that uses its filter files. My ears like the results, but God only knows what that’s worth. I took a look at DIRAC and it appears to be similar to Focus Fidelity, but perhaps more comprehensive.
As for the situationality (is that a word?) of subwoofers, my dedicated listening room is on the small side (here are details I posted a few years ago). And it’s only me in there, so all my placement and room tuning is for a single listening position. Would my Focus Fidelity software “tune” my subwoofer to my listening position as it did with my main speakers or are there other ways to find the right place for the sub?