What solution to clean silver and gold contacts?

Hello!

          I am looking for a product to use to clean contacts in my audio system. Contacts are mostly gold plated, but some of them are pure silver on pure silver.
         I do not want anything that leaves any kind of residue / contact enhancement product. I read on forums that some members claim these products improve the sound at first, but later degrade it. So in the end, they removed all of the contact enhancement product from the actual contact.
         Right now I am mostly leaning towards using pure ethanol alcohol, as I think all of it would evaporate.
         Thanks in advance for all of your advices.