If the sub comes with it's own amp.
Then we have more fun as we sort out what signal it wants. I can't guess this since the documentation is absent but it doesn't mean we're toast. It only means we have to be careful about the first power up with the volume knobs on the first amp/receiver set at zero as we power up. I can spot if I need to put in some other attenuator in the next few minutes as I turn the volume up a little. (the sub kicks in early.)