That thing is awesome! What a beast! That would be fun to play around with for sure.
As far as the PA amplifiers, I was referring to the main ones used in Home Theater (the crowns and Berhinger). Both of those have a 20hz high pass that is built-in. There was a Chinese off-brand that offered no high pass, but I can’t recall the name. Having said that, I haven’t kept up with the new Berhinger amplifiers, so it is possible they do not have one.
I can’t even imagine buying a $3500 amplifier for my subwoofers. That is insane! It sure would be cool though.