“What do they do exactly?”
Here's what it says on SR’s website:
“ECTs clean up high frequency noise that otherwise distort harmonic structures within the music signal.”
With 5 in difference places in my system, I hear increased transparency, detail, immediacy, palpability, sense of space, and musicality across the board. You know, all the good stuff we're looking for😉 That may sound over the top, but it is what I am hearing. Will you hear the same in your system? Don't know, you'll have to find that out for yourself.