Sennheiser 650 Headphone Cable Upgrade

I just purchased a pair of Sennheiser 650 headphones. I was debating on upgrading the headphone cable. For all 650 owners, did you upgrade the cable and was it 'worth' it? I'm trying to stay under $300 if I decide to purchase an upgraded cable. Strictly casual listening through an iPod or my Marantz receiver.

Also, what cable manufacturers do you recommend (i.e. ALO Green Line, Cardas)? I'm sure there are others, but that's just what I found. Any other recommendations would be greatly appreciated.