Bought the wrong subwoofer!

There’s gotta be a way to connect the sub

I refuse to believe a receiver has no way to connect to a sub 

https://www.crutchfield.com/p_543ADP12/Russound-ADP-1-2-Speaker-level-to-Line-level-Adapter.html

There are speaker level to line level adapters. There seems to be some disagreement over whether you need a second set of speaker terminals to connect it to or if you can piggyback it to the same terminals that are driving your main speakers. I think this would compromise the sound of at least your subwoofer if not the mains speakers as well but don’t know just guessing. 

I can’t return the sub because I bought it from the original owner who also bought and didn’t use it. Also don’t have the box.

Call SVS and see if they have a seller/buyer warranty transfer policy. You need the serial number. Power Sound Audio has a seller/buyer warranty transfer policy that’s good for up to 5 years. And SVS has their own policies too and you may be able to return or trade up for one that suits your needs. Wouldn’t hurt to try.

If you can’t return it to SVS, I think they also sell the boxes for their subs for shipping, as this scenario happens all the time and then you can re-sell to anywhere.

Hey - this will fix your problem.I have this on a very high-end system. No issue. OR you can contact Vermouth audio and ask them to make you custom "y" wire.