Question for sub woofer users

I'm a REL fan of course, but I do question their claim that the High Level input reproduces the sound of the amp. I certainly uses the signal of the amp but since it then goes through its own amp this claim seems like hype…understandable, but hype nonetheless, and with low frequencies likely not a big deal anyway as low frequencies generally rely on higher tones for aural specificity (!) and much of the overall tonal character unless the sub is very poorly designed.

One thing no one seems to mention but that I think is very important  is phasing the sub properly. Soundoctor.com has plenty of info on sub setup.
He is the tech support guy at JL Audio. They know a thing or two about subs.

One thing no one seems to mention but that I think is very important is phasing the sub properly. Soundoctor.com has plenty of info on sub setup.
He is the tech support guy at JL Audio. They know a thing or two about subs.

Great site!  Thanks!

Technically they are supposed to be set and forget. But I find they need tweaking depending on the program material. Nothing to do with the other equipment, just variables in the recordings.