A great thread
As Mr Cheese says, it's relatively straightforward (and cheap) to make a cable that adds near to nothing. There's no magic, and very few parameters to minimise.
You will definitely make much bigger changes (and frequently, improvements, though I have made a few changes that I've changed back!) inside the equipment as there is so much more going on there than there ever can be in a length of wire, and because the equipment is always a price point compromise.
The CD63 / SE / Signature versions are all attempts to improve (or at least justify an increased price!) but they are not subtle tweaks, they are engineered improvements (for the most part - some are snake oil). Once you have a cable with low reactance and low resistance, thats it. End of. You can't do any more - unless you believe in painting them green or adding oak boxes along their length.
Here's a challenge for you. Sort out the clock in your CD player. Reduce it's jitter and phase noise (if that means buying a new clock and fitting it properly - I've seen some bad jobs - so be it) and then tell me it doesn't improve things tenfold over what any cable can do and I'll eat my own poo!
"Two very small men cutting steps in the roof of the world"