By the way, I think time and frequency correction is very cool. However, there’s a few points I want to make.
Many speakers are just not very neutral in the frequency domain and an EQ is the only way to fix it. From B&W to Martin Logan, some highly touted speakers are not objectively neutral. While we can argue about the overall importance of frequency response, it’s usually the thing people hear first and most. So, the good news is modern EQ can correct this, the bad news is it may leave your speakers sounding like something else.
Second, speaker designers know how to do time and phase matching, it’s just not worth it for many of us. If it were all that, we’d hear about Thiel and Vandersteen exclusively, and no other brands would dare compete. However it’s not the case. There are also some negatives. The hardest part about doing time/phase alignment is actually finding drivers that will let you. You need particularly well behaved drivers, AND you’ll possibly give up significant amounts of dynamic range for it since you may be limited to using first order networks.
Could I design a time/phase coherent speaker? Sure. Would I? Meh. Honestly the Thiel and Vandersteens I’ve heard didn’t do it for me enough that I gave up all other designs. Still, the idea that I can just get a DiracLive or DEQX to fix that all up for me is intriguing!
The one thing to remember too is EQ by itself is not nearly as good as with a balanced, low compression, low distortion speaker with good room treatment.
As with all things, please make yourself happy! :) This is just my own impressions and experience, which doesn’t matter a bit when you shell out your hard earned cash.
Best,
Erik