RCA Y

The gold plating makes a solid connection when I push both cables in, and my subwoofer finally gets the full signal it needs. Took seconds to set up, and there's no buzzing or looseness at all.

Grabbed this to convert the two RCA outputs on my sub cable into one input, and the connection is tight with no hum at all. The gold plating seems to be doing its job since the signal stays clean.

Used this to combine the left and right subwoofer outputs into one cable and it works perfectly. The gold plating feels solid and the connection is snug with no buzzing.