Love your DIY speaker cable. I haven't gone nearly as far as you, but I too am using an outdoor 3-prong extension cable for my speaker cables. It's 14-gauge, and I'm using the black wire for the negative terminal, and the green/white for positive. I think it sounds great!
Are you still using the Decware CD Player? I'm not familiar with it, but it looks like a stock CD player modde with a tube output stage. I've done something similar with an old NAD 502 cd player. Love the sound!