My experience with both speaker and interconnect cables is that they can make a big difference, in fact can be the most cost effective system upgrade money you can spend, dwarfing the cost effectiveness of upgrading electronics (which I've done plenty of). If someone's ears hear differently, so be it, although I don't see the logic in telling others how their ears should hear or that they are fools because of how their ears hear. As for solid silver vs solid copper vs a mixture, I have had all and have been impressed with all (in varying degrees and combinations). So, rather than coming down clearly on the side of one or the other, I feel that other factors, like the overall quality of design, material, construction and manufacturer, application, other equipment, etc., i.e. what others have cited above, all go into making a decision.
Jim Heckman
