It all comes down to several factors. The HD800 can be said to be very analytical and forward sounding headphone. It is very much like an electrostatic headphone, in that it is light on it's feet, detailed, crisp and a little light on the bottom end depending on the amp you use. If you are using a forward sounding solid state amp, then the Silver Dragon V3 is not the best option as it will just accentuate these forward traits. But if you are using a warm lush amp, like I am using, then the Silver Dragon can be of great benefit. I use the Cary Audio CAD 300SEI amplifier which uses 300B tubes and is very warm lush and liquid sounding amp. I love to use silver based cables with tubes. As it livens things up but still remains true to the romantic sound. So for me it makes sense. The Silver Dragon V3 is very detailed, has lots of air with great transients. If you are a detail freak like me, then it is for you. The Blue Dragon V3 is a very neutral, natural sounding cable that is not overly warm like say the Cardas headphone cable, which we also sell. It will improve detail and smooth out the sound. It has been the most popular HD800 cable. We are now able to finally provide the Black Dragon V2 as an option for the HD800 as we have a connector now that will handle the larger conductor. The Black Dragon builds upon the sound scape of the Blue Dragon but adds a fuller sound with more bottom end weight. This cable will probably prove in the future to be the most popular of the ones we sell/build. More infr on these cables can be found HERE There are plenty of reviews of these cable in out feedback forum thread.
Hope that helps.