Distributed Bass Array configuration

You're twisting it around MC, the whole purpose of level matching is to prevent you from trying to figure out what the volume on the subs should be. That's why its called level matching.

@mapman wrote:  "I think its a fallacy if some are asserting setting up multiple subs properly is easier than one."  

@golfnutz wrote:   "I agree, using the 'throwing darts' method isn't the way I'd install a $3200 subwoofer system." 

I realize that it seems counter-intuitive to think positioning four subs in a room is easier than positioning one, but consider this:  When you change the location of a single sub, you have changed the way ALL of the bass energy is introduced into the room.  With four subs, when you change the position of any one of them, you have changed the way ONE-FOURTH of the bass energy is introduced into the room.  By following a few guidelines you can probably end up with excellent results after one or two adjustments, if not from the get-go (which seems to be the case about half the time).  I include six different setup strategies in my guidelines, most of which are very forgiving, and all of which have been used successfully.   

Regarding setting the levels, either ears or measurements can give excellent results, but in either case (and regardless of the number of subs involved) finding the exact setting IS critical.  The reason is, the ear's heightened sensitivity to changes in SPL at low frequencies.  A little bit of change in gain on the subwoofer amp translates to a disproportionate change in PERCEIVED loudness.   So it may take a while to find that magic setting on the amp's gain knob.  Note that measurements alone may not be enough - Geddes and Toole and others have observed that most listeners prefer slightly elevated bass compared to the rest of the spectrum, but the amount of elevation preferred varies.  I got excellent results fairly quickly in a challenging situation by using measurements as a starting point and then having an experienced bass player guide me as I fine-tuned the settings.  

Note that the improved in-room smoothness of a distributed multisub system allows more flexibility in setting the level.  It is the peaks which stick out like sore thumbs and are the limiting factor in how loud we can set the bass before it starts to sound unnatural.  Smaller peaks means that we can set the level a bit higher for more satisfying bass because we don't have to sacrifice a truly satisfying level across the rest of the bass spectrum to avoid over-energizing the peaks.  

Duke

I have found the best and most efficient way to set up a sub is to measure first to get things in the ball park and then fine tune by ear from there.
What I get out of the whole DBA thing is measure before doing anything. It may be a waste if peaks are not a big issue. There will always be some though so it’s all a matter of judgement.
If the goal is to smooth things out at just one spot, DSP is probably the most straightforward solution. Or a good old fashioned analog parametric equalizer.
For smoothing out across the room then the more heavyweight dba solution might make sense, but only if the mains are capable of delivering across the room as well ie they have wide dispersion characteristics otherwise you might have smooth bass across the room but everything else falls short.

Then there is the alternative where you have multiple subs set up not  primarily to smooth out response but for best soundstage (smoother response is a secondary benefit).  That means if 1 sub front dead center,   2 subs at or near position of mains, 4 subs the two behind you are set to a lower level than front.  

I agree, level matching the subs to the mains is a good starting point, especially from someone installing their own subs. Where you end up doesn't mean the same position is necessary. At least you'll know where you are with reference to increasing or decreasing gain. Each time you add an additional sub, the SPL increases. So if having 4 subs (or more) in a room, I would think level matching becomes even more important, especially, as you said, if you have a difficult room.

Flat in room and or at listening position is just a starting point for great bass. Time, phase and Harmonics and the superb transition to mains with high pass is crucial. More sources ( subs ) in the room is a simple averaging machine for amplitude… great for sine waves… not so great for the rich harmonics above the magical oft cited 80 HZ line.  This is a big hint…. Play a decent recording of a scaling acoustic bass w eyes closed… image move ? (!Wales gets it, Eric surfed up next to it w Orchestral, a small Cello ensemble… I am guessing it aint all mono for them ) Glad the OP is at 95%, wonderful place to be but like any good audiophile questing for even better !!
of course use test tones, rta, good microphone… and listen. 
Fun thread but needs more cowbell and bass players…