Preamp to Amp jumpers on Bryston Integrated

I'm going to experiment with a subwoofer and need to split the "preamp out" signal to go to the powered sub (plus go back into the amp input).

Is there a reasonably inexpensive way to do this without investing hundreds of dollars in "audiophile jumpers" plus splitters?

Currently, like a lot of integrated pre/amps, there are a couple heavy copper like wires going between the RCA outs.

Thanks!