Headphone jack adapter; more spacing between L & R

I use Purist Audio cables, which have big, beefy RCA jacks on the end. I am running them between a Nuforce Icon and powered Mackie speakers. As a reult, I am using the headphone jack of the Icon so I don't over-power the Mackies.

My problem is this: when I buy headphone adapter jacks that have a left and right input, those two inputs are soooo close together that it's tough to fit really big jacks in there.

Does anyone know of a headphone adapter jack where the left and right inputs are spaced far enough apart to handle big RCA jacks?