Active line level crossover with subwoofer out - HELP

And finally cut is your friend, boost can really ripple... on a well thought out analog EQ cut is 2x boost....

Also, no matter the route you go ruler flat rarely sounds best - especially in the analog domain.

Indeed, you, Fred Toole and I agree on this. Fixing gross abnormalities in the bass region is often all you should do.

Whatever route you go with EQ : DSP or analog - get you best signal to background noise possible - run EQ in the hyper low noise wee hours of the morning.
very few audiophiles understand the baseline s/n of the room they listen in. Use the slow weighting on your SPL meter...

for many this may also lead to the realization that noise management may be a much much bigger sonic improvement than an expensive power conditioning gadget... of course, some of us do both....

Doing this when it's quiet is important, or you'll try to EQ your air conditioner.  :-)

Using OmniMic or Room EQ Wizard can be a lot easier and faster than attempting to us an SPL meter though.