08-27-14: Psagtrue if you have reasonably good drivers that need correction to make them sound their best.
Optimal phase and timing correction can only be done in the digital domain. All dynamic drivers are subject to these errors, and there is no conventional crossover or driver design that can correct this to the extent that digital correction can. That's one of the reasons why DEQX will enhance the performance of any speaker.
OTOH, if you have superlative drivers that are already linear between the frequencies they are crossed over then DEQX will not add much at all.
All depends on the skill of the speaker designer - the better ones don't need DEQX; most of them do.....