Oh sorry, the C5D is an portable amp made by JDS Labs.
I just looked on ebay.
http://www.ebay.ca/itm/New-Replacement-Audio-upgrade-Cable-Stereo-Cord-For-AKG-k490-NC-K545-headphones-/281403603067?var=&hash=item4184f6387b
mTWqTZTlwEb0no9P-QyOgpg
http://www.ebay.ca/itm/Generic-DJ-Coiled-Audio-Cable-For-AKG-K-490-545-845-Y45BT-Y50-Y4-Headphone-2-5mm-/261978675738?var=&hash=item3cff255a1a
m86LYX6kPX3hayKeIXglXdw
http://www.ebay.ca/itm/Replacement-cable-with-Remote-and-Mic-for-iphone-to-AKG-k490-NC-K545-headphones-/281628887808?var=&hash=item419263cb00
mlcjmym_wmmlFFjUKeHkTwg
http://www.ebay.ca/itm/New-Cable-with-Remote-Mic-for-Google-Nexus-4-5-7-to-AKG-k490-NC-K545-headphone-/311319444297?var=&hash=item487c15bb49
mf_xj3bnrt6RJqjXgeqA7tg