What process did you use to integrate multiple subwoofers for 2 channel listening?

How high are you crossing the subs? Looks like it drops between 90hz and 500hz and another big dip between 2khz and 10khz. What does a measurement without subs look like? 

@djones51 In the image I posted yesterday -- which I didn’t label specifically enough -- the orange "morning" line is speakers only.

Improvement from "Morning scan, without subs" to "Afternoon scan, with subs" mitigates the dip significantly at various points, e.g. pulling up a null by 10 db at 129 hz, by 8 db at 241hz. At other points, the later scan makes some things worse, but overall, the subs were helping.

Morning scan, there's another big dip between 2khz and 10khz. Afternoon scan mitigates that by a very large amount (varying, but up to 7 db mitigation).

a good quality parametric equalizer or DSP would really be the simplest and most cost effective way to fix things in a problem room rather than a complex sub setup in a system that does not seem bass starved to start with.

I know, I know, more stuff in the signal path. So what? As long as its good stuff? Audiophiles get too anal about these things sometimes. THe end result is all that matters. With digital anything is possible. Them’s the facts!  Digital is your friend!  Stick some tubes upstream if you must.

Whatever works best.

@mapman -- I'm not against it, absolutely, but want to see if I can make a casserole with what I have and with the skills I have. I've spent a fair amount to have more than decent cables and DAC, so to add something into that mix is not necessarily about "polluting" the signal so much as adding an element that will change the character in unintended ways, even as it may be correcting other outcomes. But I hear you. Not ruling it out.

@tvad  That's a good object lesson. And I'm not aiming for Howard Hughes levels of cleanliness in line response. My issue is that I can hear the bump that I see measured. I tested that out last night -- I found a track of acoustic bass on a Chesky recording that goes up and down the scale, knew instantaneously where the muddy/tubby section was, measured the frequency of those notes on an analyzer and then compared to my REW graph. Exact match. If I can at least manage a couple unwieldy peaks, I will not have lifeless music, but I will eliminate flaws which my ears can hear. That's the goal.

That said, we all remember Hawthorne's short story, "The Birthmark," where his otherwise beautiful and kind wife has a birthmark which the protagonist insists on removing? Spoiler alert: the process kills her.