Ferminx: Parts Connexion or get Moon Audio Silver Dragon. In both cases it'll be expensive.
I was at my local DIY parts store looking to make a special TRS to RCA adaptor for my ULN-2 (it must have the ring not connected) and found a TRS plug that PERFECTLY fits those small, cheap generic RCA sockets. I could literally screw them in place inside the plug! I only had to bend the tab for the wire on the inner ring 90 degrees. Having that actually made it easier to drop the nut in and screw it tight.
Edited by Currawong - 3/31/13 at 3:44am