digital eq/room correction trade-offs

I'd suggest to

Step 1: find a good mains positioning and listening position so that you can run mains full range and untouched - the straight wire and gain approach.

Step 2: find a good spot for your subwoofer that gives you again the least suckouts in room response when combined with your main speakers - run the sub up to 80 or 90 Hz.

It is important to worry about the suckouts because ultimately you don't mind the bumps so much as you can EQ these down. Whilst the suckouts are gonners and may create "holes" in what you hear - a bass note nearly disappears for example.

Step 3: Apply precise narrowband notch filtering (with any device of your choice) to the signal going to the subwoofer.

If you have paid careful attention to the 100 to 300 Hz range when setting up speakers and sub position then your notch filters on the sub (20 to 90 Hz)should get you pretty close to flat.

Although this process can take days it is worth doing.

=> Be psychologically prepared to be slightly disappointed when your previoulsy favorite demo track with that absolutely awesome devastating pounding earthmoving bass note - that jumps out at you and your neighbours every second or third bar - suddenly sounds tamed and controlled and musical (instead of a gong show).

==> be psychologically preapred to hear more ambience cues and more details in the lower midrange that you did not hear before.

====> be psychologically prepared to discover that you can easily follow bass player notes cleanly, evenly and clearly

FWIW: A precise sound is NOT as impressive in terms of "sound" unless you retrain yourself to focus on the musical details (a musician's careful accenting on particular beats in the bar) rather than the odd musically unrelated kaboom emphasis as a the note happens to hit a room mode.

As a corollary to what I said above - part of the reason people change gear so much and like re-mixes/re-masters by clever musically trained sound engineers is that they get a different accent on the musical experience - it changes where emphasis was made. The room does this too. In a sense, the new equipment or the same equipment in a new room creates a new version of what is heard with sometimes hugely wrong (but pleasing to some listeners) differences in emphasis.

Nothing can completely control all this - but measurements and careful attention to gear selection can get you, on average, much closer to what was intended or heard by the persons producing your recorded music. Whether this is worthwhile to you or not is debatable as there can be pleasure in creating new interesting sounds or changing emphasis to make old sound new (even if it isn;t close to what was originally produced)