Sennheiser CH 700S

If you owe Sennheiser HDVA600 or HDVD800, get it

Here is my two cents, I don't believe expensive cable/wire will make you headphone sound a lot better. Most likely you may (I said you may) recognized the different, but it does not mean the better sound.
In the case of balance cable, its different technology, not just wire material, you get extra power or whatever that make your headphone sound louder, As a result, at the same volume, you hear a louder sound with balance cable vs regular stereo cable. In other words, the amplify will drive the headphone more efficient when you using balance cable. I prefers to use balance cable with Sennheiser HD700. Another reason I buy this cable so I can use all four headphone outputs to share with other family members. If I can buy similar cheap balance cable for $50.00 I won't buy this cable. I also use this cable with another adapter on Sony PHA-3 portable amp, and it makes a big different due to extra power