One truth about working with audio is you always need the cable or adapter you don't have in your toolbox. That's why we love these terminal-block audio connectors so much. No soldering required! Use stranded or solid core wire and a small screw driver to create custom wiring jigs.
This is the 1/4" (6.35mm) Stereo Plug Terminal Block. It's a pretty common size and is super useful for more heavy duty connections - like a modular synth, amplifier or an electric guitar.