Just to add to what Bigkidz mentioned, there are alloy IC's which eliminate the debate about which single metal can be made to sound best.
My favorite manufacturer in this category is Auricle Audio Design, and when auctions end "his prices are insane" to borrow a word from Crazy Eddie's long departed television ads. Or, one could say these designs are "insanely great," a phrase added to popular culture by Steve Jobs of our modern era.
The low auction bid prices are a tribute to Audiogon's appeal to me -- great items hiding in plain sight don't have to cost what they're worth.
I have successfully inserted in more than one system, and more of what each component can deliver becomes evident. In a well assembled system be prepared for a pleasant shock.