Best use of Red Dawn interconnect

Is the Red Dawn interconnect best used between CD player and pre or between Power amp and pre?
Only you can answer that. Different components react to cables differently.

Also keep in mind that whereever you put the Red Dawn, you have to put another (different) cable in the other position. Either way the signal is passing through two cables. So maybe the Red Dawn currently sounds better coming from the CD player; but would actually sound better in the pre/power position; except for the other cable you are using sounds really bad used for the CD player.