If you're making your own cables and don't want to use silver, you might try the Canare L-2B2AT copper cable. Pretty small (though not quite as small at the Belden 1804a) and very flexible.
Personally, I don't find the Belden 1804a to be unpleasant sounding, but it isn't at all the same to my ear as the milspec teflon silver cable that is often used. I think the teflon dielectrics might have a lot more to do with the signature sound of the silver-clad copper cables many are using than does the silver itself. (The Belden 1804 doesn't have the teflon insulators, though it is silver.)
The teflon milspec silver stuff is fairly stiff, so if you want flexible, that would be out.