No need to put panels in back of the speakers. The common description is "live-end, dead-end" one end of the room some be untreated (live) the other should have treatment (dead). Also, I don't believe Audioquest ever used OCC copper. They use something called "perfect surface" (?). Harmonic technology, Acoustic Zen, Wireworld and, recently, Shunyata all use OCC (single crystal) copper. BTW, Aluminum tweeters are not necessarily harsh.
Good luck with your quest...
Good luck with your quest...