rel subs are best used with their high level input, but they do have lfe/rca inputs as well
it would be safe to say any modern rel sub would be plenty fast for any application where the main amp is a sonos amp (provided the user follows instructions and properly integrates it/them)
there are some people who don’t get the integration correct, while others unfortunately struggle with a sort of ’reverse placebo effect’ where they mentally can’t get their mind to get out of the way in allowing themselves to hear and accept that well done, subwoofer-supported bass is ’correct’...