I bought a Sennheiser HD565a while back. they're discontinued (tho still to be found at some places and worth a look if you don't have/want an amp but do want high end Sennsound. and costs less then a 580 as well ), and didn't get the connection upgrade the 580 and 600 got. I got some intermittent problems after only a few days. no biggy, just touch the contact and evrything's okay again.

someone (sry, forgot the name) recommended using some contact spray on the contacts. I found a cables-resistors-and-other-electro-stuff kinda shop in Utrecht yesterday which also sold contact spray. so I bought a can for about 5$ and enough to last a lifetime it seems

tried it at home, completely solved all connection problems really, not even a crackle if I wiggle the plugs! wow! it might occur again, but this solution sure beats the **** out of ordering a new cable

everyone with connection problems (people with older Senns, davidcotton) and everyone hesitating to go Senn because of this problem should really just get a can of contactspray

I remember seeing somewhere that Caig's Pro Gold connector treatment also works. What did you use?

This type of stuff is useful if you don't intend on spending $$$ for clou cables or a stock (replacement) one.