Cable Asylum: Try VH Audio Cryoed Flavor 2 or Flavor 4 by SoftwireEngineer

I think the Acoustic Zen should be good. Let it break in for some more time. Does it sound closed in ? that is one sign of not breaking in. You may want to check the sound with other sources. Rotel is known for its neutral or thin sound. So if your source is harsh it is going to be amplified so.

I have tried the Cryoed Flavor 2 with my AudioRefinement Int. AMp with good result. Great improvment over the whole spectrum over a simple or stock cord and slightly better than an Analysis Plus Power Oval. The Analysis Plus is a shielded design, but I could hear some EMI/RFI with it, that I was using a PS Audio Ultimate Outlet. Now with the Cryoed Flavor 2 I am going straight to the wall. The common mode noise rejection of the Flavor2 is so good. You may want to try this or the Flavor 4 if you want a bigger gauge. Because of the noise reduction and cryo you may be able to reduce the thinness/'silvery' sound.