High Level Input Confusion

So assume you have a sub with only high level INPUTS, how the hell is that supposed to work? do you sacrifice an entire set of stereo channels from an amp just to get signal to the sub, with no signal or crossover making it through to the speakers/speaker amp?

high level inputs with a set of OUTPUTS below it are pretty straight forward though. It’s just like the in/out low level rca’s for powered speakers… right?

Sub example;

Airmotiv SE8 8" Flex Subwoofer – Emotiva Audio Corporation

…ahhhhhhhhhh fuck, just remembered “spade end → banana plug” cables exist for literally this purpose.

I’ll leave the post up anyways, flag for deletion if you want (unless it gives me bad site karma or something like a strike lol)