Interesting way to wire speakers…???

WBT's lead free/silver solder(0805) is 95.5% Sn(TIN), 0.7% Cu(copper) and 3.8% Ag(silver) Their lead-based(0800) is all of 4% Ag(silver). I love WBT solders, but not for a coating on terminations.

It takes good copper quite some time to corrode enough to degrade sound, given a nice, tight crimp. The process can even be slowed further, by the use of a contact enhancer(ie: (https://walkeraudio.com/shop/e-sst-sst-extreme-super-silver-treatment-for-contacts/) or (http://www.vhaudio.com/contacttreatment.html) If the OP's point is better sound; his goal would be better served by the use of straight copper or(better yet silver) jumpers, cleaned with rubbing alcohol or a Caig's product, every few months, before corrosion sets in: (http://www.whatsbestforum.com/showthread.php?1652-Contact-Cleaning-The-Right-Stuff)

"Audiophile silver?" What do they mix with the silver, to make that? All pure silver will eventually tarnish(a layer of silver sulfide), unless plated with another metal. Soldering the exposed conductors will defeat your purposes, as most fine solders are composed of over 60% tin, which isn't as good a conductor as copper(copper's six times better).