I moved my Sennheiser factory upgrade to a Cardas headphone Cable balanced also. My 800 phones were singing far better than with Sennheiser's own cable.
I highly recommend taking a look at LavriCable as they make high quality cables at very reasonable prices and fly below the radar. I got an excellent 1.2m balanced cable with silver wire and top connector/plugs for only $253 for my Hifiman Arya Stealths and it’s a big improvement over the stock cable. Here’s a link to the cable and how I configured mine.