You could also use any length of sub/rca cable and use a short Y splitter with 1 female in to 2 male outs.
I have an old Velodyne sub like that. It said you could run a sub out to either right or left input or use a Y connecter.
Need help: Energy ESW-C10 subwoofer -- Denon Avr-s540bt receiver?
Energy ESW-C10 subwoofer
Denon Avr-s540bt receiver
Subwoofer doesn't have subwoofer cable input (older), receiver does for two subwoofers, looking for the right adapter to connect the two correctly, hopefully sound quality doesn't degrade.
Subwoofer has left right line in (___ technical name) and speaker level in.
Thanks for the help