Hopi,
I have a couple of pair of More-Me's just for this purpose: $20, and aren't hi-fi etc., but suffice for extra cans, and at the price, disposible ones. One caveat: they have a very short cable (6") but actually is a great design - the "talent" can never step on the cable, ripping the innards out - the 1/4 (or 1/8 )" connector just comes out instead of the headphone guts!
Contact Harvey Gerst - he makes them, and offers repair/replacement for one year!
Harvey@ITRStudio.com
Hope this helps,
_________________________
Jay
PlugHead Productions