Here is my speaker cable upgrade path in my two channel system:
2003-2007 - Monster Cable Z3 Reference, $300 per 10 foot pair.
Sept. 2007 - PS Audio xStream Resolution Reference, $800 per 3 meter pair.
Nov. 2007 - AudioQuest Volcano 72v DBS, $3,300 per 8 foot pair.
Jan. 2008 - AudioQuest Everest 72v DBS, $11,700 per 8 foot pair.
Sonic improvements as I went from Z3 Reference to xStream Resolution Reference to Volcano to Everest are described in these reviews:
I think it is important to maintain a rational perspective in any hobby. When I started studying saxophone, I did not start out with expensive professional quality or luxury grade instruments. When I started studying photography, I did not start out with professional or luxury grade cameras, lenses, and film. In music and in photography, I started with equipment that was appropriate to my level of skill, experience, and understanding. I did not concern myself with how much money serious, more advanced hobbyists and professionals were spending on their gear. Even if someone had gifted me a pro quality camera and lenses in my early stages of photography, I would not have been able to appreciate all of its performance advantages over the entry level cameras and consumer grade film I was familiar with. The same would have been true had I been gifted a professional grade saxophone when I was first learning to play or a Mercedes Benz when I was first learning to drive.
I must admit that I am always puzzled by the apparent fascination that some people have with high performance and luxury grade audio equipment. I was never any more fascinated by high end audio equipment than I was by high end anything else (shoes, clothes, furniture, cameras, musical instruments, cars, etc.). I never wondered if higher end merchandise was "worth it". I took it for granted that it was, otherwise, there would not be a market for it. In every field of merchandise, there is a class of experienced and knowledgeable enthusiasts who seek high performance in function and aesthetics.
In audio, as with my other hobbies, I started with very modest equipment and upgraded to more advanced, higher performance (and, of course, higher cost) equipment over the years as my interest, knowledge and skill increased. There is nothing mystical or supernatural about my audio journey. I do not have superhuman hearing or "golden ears". I can discern and appreciate the performance advantages of high performance stereo equipment simply because I have trained my mind and ears in stereophonic perception. In other words, I have listened to a lot of different equipment over a period of time. Careful and consistent listening causes your ears (perceptive abilities) to evolve.