@erik_squires Thanks for spending the time to thoroughly explain those issues. I can easily turn off smoothing, but at some point, the curves get so crazily jagged (with no smoothing), that I'm not sure what I'm supposed to take from it.
I haven't figured out how to turn off gating yet. Trying to research that now.
@lemonhaze Thanks for your input. When you say "some absorption", do you mean bass traps? If so, are there more economical solutions than the $500/bass trap solutions from GIK?
Yes, with minimal treatment of the room, there's a definite tradeoff between dips at 58Hz and 180Hz. If I move my LP so the 58Hz dip fills in a lot, it creates a smaller dip at 180Hz. You can see that 5 posts above in the 60" LP vs 45" LP.
I do see that 35Hz peak in the many of the plots posted by other people in different rooms, so that one seems common. The other ones seem more variable and a matter of trade offs.
In a room my size and filled up with record, CD, and gear cabinets as much as it is, I think it's honestly unrealistic to entertain getting two new non-ported subs. I understand there's a proper way to do things, but I think the question for me is what gets me close enough or good enough to live with while still keeping my room as usable as possible.
Because if getting things closer to ideal requires my stepping around subs or having to contort to access my media because a sub is blocking clear access to a rack, then it's going to be a daily irritation. Not sure I mentioned above, but this room is also a TV room with Atmos in-wall/in-ceiling speakers, so I'm admittedly trying to do a lot with the room and one of the consequences of that may be I'm not going to be able to do things as ideally as a pure 2-ch listening room.
I do have a single HT sub (SVS 10" ported sub) and I could dual purpose that if it would help. It does have a phase dial. Since I'm using older gear, I'm going to need to sum my stereo signal to mono and then route it to my sub (no speaker level inputs on my sub, just a single RCA). I could play around with that and if I see the potential, maybe I start to think about how to move some things out of the room and consider a couple of ported subs.
But the room just isn't all that big to begin with unfortunately.
All that being said, I am open to room treatments, preferably beginning with ones that are highest bang-for-buck and seeing how much that improves things before going too far down the rabbit hole and diminishing returns.