 Hi, It is interesting to share experience. I could assure that the coin and tube you used created a real difference rather than a psycho acoustic one.
After Joe tweaked my system, he was also kind enough to bring me along to some tweaking occasions. He also introduced me to some systems of his friends who he is familiar with. All of them are eye-wide-opening experiences. What is more important to me is, I've learnt to better appreciate and become more sensitive to 'differences'. I've found these differences sometimes beyond just the sense of 'hearing'. But still when compared to Joe and his friends, my senses are still too blunt. Sorry, I still don't have golden ears though I think I'm better trained than before. Taking Joe's advice, I've put a piece of really heavy metal on the MDF which my power amp is sitting on. It was the section of the joint of a pipeline weight over 15lb. Holy cow, the improvement in focus and mid/bass is dramatic. Now the drum from Hotel California shatters my window. But wait, there's no free lunch. The high is less extended and the pace has retarded. These few days I'm figuring out how to recover these drawbacks. Just to share more. To get better bass extension and quieter background, try putting a piece of amethyst (ie purple crystal) cluster on top of the in-house circuit breaker box. I bet it costs a few ten dollars? It really works. But to get even better result, you might have to pay more - get the AU-24 interconnect and you'll know what I mean...Cheers! | 
