This isn't anything new but I went with a different approach today...
XM auxiliary jack mod.
Instead of using a head phone jack and then having to use a intermediate cable with two male ends I cut out the middle man.
Here's the route I chose to take...

This is the ONLY material I needed minus the tap connectors.

Cut each end connector off and then twisted both of the ground wires together for a common ground.

Use the same ol tap connectors for the speaker wires and the ground

Plugged it back in and dunzo funzo.
I know the mod is a century old but just threw my own twist on it.