I need a 20 or 25 foot headphone cable

thanks Swamp...I guess I never thought about just getting an extension...that'll probably be easier & cheaper. take care.

Its called a headphone extension cable .Available everywhere.E Bay,BB,CC etc.Very common item.

I use a 20ft. Stefan AudioArt Equinox cable with my HD 600's. Prior to that I was using a 10 ft Cardas cable with a Grado extension cable. I would try to avoid an extension cable if you can. The weak link is the connectors in the cable. You're much better off with a long cable (no additional connectors). But once you plug them in I would leave them. Plugging unplugging, plugging unplugging, etc. will take its toll on the 2 prong pin plug to the headphones. BTW, the Equinox cable was a big improvement over Cardas. It's pretty expensive, and a long wait to boot, but worth it IMO.

Drew at Moon Audio will either make you a Senn cable that is long enough for your purposes, or sell you a headphone extension cable. He makes 'em in three varieties I think and they are all of excellent quality. Not a long wait either. http://www.moon-audio.com/
Personally I would go for a long headphone cable, not an extension, as I tend to accidentally pull the plug out of the extension if I move around or lean over to pick up the remaining sections of newspaper I am reading etc.

The Moon cable is very good. Never hear the equinox.