Bombaywalla,
You are right, we did have a lengthy discussion with Roy on the topic, and he did say that about processors...including DEQX. But my take was his answer was based on speculation on his part as to how these devices work. He didn't come through as if he had actually tried any of these. He is a believer on time-alignment and has developed analog XO to do that at all frequencies, and I think he believes measurements cannot deliver the same and the differences are significant enough. But from people's experiences here with DEQX and elsewhere with Acourate, users are very happy compared to their situation pre-digital device.
I've been in touch with a guy who has a very expensive system with YG speakers, etc, and used to own a TotalDAC D1, which he replaced with a DEQX HDP-4 and was super happy about the change and couldn't talk highly enough about it. He now replaced it with a Lynx Hilo and Acourate and now he can't talk highly enough about that setup. I am by no means suggesting the latter approach is better than the DEQX, but his experience shows good results can be achieved either way. And the multiple good reports also suggest measurement-based approaches indeed work, even if suboptimal vs Roy's approach.
BTW, I've been slow to implement any of these for several reasons. I was considering an exaSound e28 (8-channel DAC) and bought a used e22 (2-channel) to try out and concluded the e28 would not be a good path. Plus I live in a country where getting all of these things is super complicated - takes a lot of time.
Nevertheless been enjoying this thread and the good experiences shared here.
Cheers