I need a 20 or 25 foot headphone cable

I know this probably defies reasonable length soundwise but I need a 20 or 25 foot headphone cable for my Sennheiser HD 580's so I can listen in another room. any suggestions for how or where I might find such a beast?
I would like to be able to simply change from my short (stock) cable to this long one for those instances so connections on the headphone end are critical.

thanks in advance & cheers!