Pure Silver Wire

It’s a good question.  You’re showing 4N silver cable I think, but better silver goes up significantly in cost that'd obviously drive the cost of those cables up a lot.  I have this theory that manufacturers largely use copper cables/interconnects to  voice their products so when consumers use silver cables the increased level of information can become too much and as a result sound a bit bright.  I personally use silver interconnects but Acoustic Zen Satori shotgun bi-wire cables that are copper.  I reviewed Voodoo Ultralinear silver speaker cables in my system 20 years ago and found them to be excellent if a little less robust sounding than my AZ cables, but for someone looking for more detail/air their cables would be a great place to look. 

Cheap silver interconnect and cables are incredibly harsh. Good silver cables require a lot of design work with the kind of wire, geometry and dielectric casing. Maybe there is more to it than that. Silver cables have been both the very worst cables I have heard and the very best. The very best were real Nordost Odin 2... simply stunning... not remotely harsh, detailed and natural... $17K a pair.

Silver is a better conductor which is important when conduction is the only issue.  Now I don't recommend using a poor conductor for interconnects and speaker cables, but conduction (opposite of resistance) isn't the only concern in audio.

Silver is 7% better conductor than copper, so by making the cross section 7% bigger you get the same current carryng capability with copper.

I recently tried some very high quality silver plated copper 8 awg speaker cables, expecting them to be awesome.  they were very harsh...now many people don't realize what harsh it--harsh is when the upper frequencies are much louder than the lows and mids.  So those nice heavy speaker cables are destined to become a nice heavy power cord.

As others have mentioned, silver is often reported to be harsh in analog cables (note this does not apply to digital cables since digital signals are 1s and 0s so lows and highs are transmitted equally.  I highly recommend silver in digital cables). 

Different grain structures of copper seem to give the best performance.  

Jerry