Congratz! They’re my favorites. 
I have both the Copper and Silver upgrade cables, and I don’t think they sound different. Nothing I can pick up on anyways.
There isn’t any, according to Meze themselves.
I eventually settled for a Schiit Bifrost 2 + Feliks Audio Euforia. I shared an in-depth review on the Euforia where you can read more of the context behind that decision: Feliks Audio Euforia - Official Thread - #2 by Jsim
Happy listening!