I have no experience with Castle loudspeakers, but have intimate knowledge of the Jolida 302s. I have found that most people prefer a detailed, forward, punchy cable with the Jolida 302A/B. Possessing a fullness at both frequency extremes. It seems that your impressions fall right into my experience, from your reactions to the 12 gauge wire you inserted into your system. I would not recommend Goertz, as I do not feel the match is very good at all. I would look to AudioQuest(Type 6, Indigo, Crystal, or Midnight), Axon 8, or Kimber(4TC/8TC). Buy the best model you can afford from the manufacturer you choose. I think you will be more than pleased.
Speaker Cable Jolida302a/Castle Richmond
I recently got a Jolida 302a and Castle Richmond speakers. for the present I have just 'doubled up' some 12ga speaker wire to have maximum conductors between the amp and speakers. It is such a leap from what I was listening to before that I am very pleased however I would assume that some speaker cable upgrade would produce a difference. Any suggestions that won't cost the same as the total of my system? I've thought about Nordost Octava or AudioQuest CV4 or Type 4+. These all seem to be in my reachable price range.