I guess this recent post of mine sums up my thoughts:
As far as the cable itself, I choose copper for the ground for both reasons. For one, although I think the ground wire material does affect the sound, its impact is minimal - probably only with the highest-end equipment (like B22) will it become important. So it seems a little excessive to me to use silver there. And secondly, silver wire - even Jupiter wire, which I like the best - has a lot of clarity and air but can sound a bit glassy in the upper frequencies. Copper tends to have a more even, robust sound to me, so using it in the ground can balance things a little bit.
This is just my opinion, which is fairly middle of the road. Some people will tell you the ground wire is 100% as important as the signal wire and prefer all-silver. Others may think that, but prefer copper all the same. And then there are those who think that all wire is simply moving electrons from A to B and it doesn't matter at all what kind you use (apart from shielding concerns maybe).
I guess experimenting on your own is the only way to find out where you fall in this debate...still, I wouldn't make a bunch of cables all at once unless you have time and money to burn. Just make something that's good, as you currently understand things. At some point in the future you will have reason, or at least an excuse ;) to make another one, and then you can try something new. That's how I learned...through making several cables over the last 3 years.
Edited by slowpogo - 5/7/10 at 4:17am