Thanks for all the insight.
I'm going to try it between the preamp and amplifier first. I would think that that cable would be the most important, but I don't know. It would seem if the better cable was upstream, and the lesser cable downstream, it would seem the lesser cable would negate the better one.
Would it be true, if the better cable is between the preamp and amp. That all of the components would benefit from it being as it's the last IC cable in the chain?
Whereas, if the best cable was between my Dac and pre amp, that circuit would be the only one to benefit from it. Whereas the other way all components would benefit from it....
I will be trying both ways, and will report back....