when I chose aluminum for the negative cable, I was not prepared for the shocking improvement of my sound over the Anti-Cables I had been using.
1) Why should the introduction of aluminum cause the sound to "improve"?
2) Especially if the alleged "improvement" were like the unkinking of a hose, allowing "more music" to flow through your system?
Aluminum offers more resistance, not less, so the likelihood is that you would get less signal, not more, that you've actually mistaken a kink in your hose for an "unkink."
3) How much distance is there between your positive and your negative? If the two are separated, you may have simply created a tone control, in which case, it is even more likely that you simply mistook the attenuation of signal for the opposite, an increase in signal.