Wife is getting home a little later than me today, so I was able to shake things up a bit. Quickly found the limits of the UMIK-1 at -11 master volume. Audyssey put me at -8.5 on the sub channel after I lowered the subs 12 dB in the miniDSP. After Audyssey, I returned the miniDSP to 0 dB, and added a house curve shelf resulting in +6 dB at 10 Hz tapering down to 0 dB at 80 Hz. I also bumped the sub channel in the receiver from -8.5 to -5.5, giving me a total hotness of +15 dB overall on the subs, increasing to +21 dB overall at 10 Hz if you include the house curve. Yeah, I know. I actually dialed it back to -11.5 in the receiver for a total of +9 dB on the subs (plus the house curve) during Captain Marvel with BEQ, it was a little too much otherwise.
Anyway, here we go:
The weirdness around 20 Hz happens with any subs, I think it's some kind of room effect. I have tried to EQ it out in the past, and it just gets weirder, so I'm leaving it alone.
I have attached the .mdat to this post if anyone wants to look at some crazy-good distortion numbers. They only get a little out of hand on the very last sweep, which had some mic clipping and probably shouldn't even be counted.
I looked for the 60 Hz buzz (which again, I can only hear with my ear against the grill cloth) on the REW RTA and didn't see it against the background noise. With Spectroid from my seat on the couch, you can see the energy at 60 Hz, but not hear it in any way. The first image is with the subs on, cables plugged in, but no signal sent:
Then, I turned off the receiver/subs and got this:
So yeah, I have detectable noise at 60 Hz, but I'm much more inclined to blame my cheapo cables (which run alongside power cables at some points) and maybe the miniDSP than I am the sub itself. Maybe I'll order some shielded cabled from Blue Jeans, maybe I won't. It's not a real issue I need to solve, so I won't worry about it.