What do I mean?
Well, AC power before the transformer, even, is symmetric and at a very highly controlled 60hz.
I simply can't imagine a fuse having an audible effect based on orientation in this application.
Now, my panels have fuses and they are goners. The crossover jumpers have been replaced by copper....instead of the chrome plated steel (!) which also helped.
I guess I just have trouble with fuse polarity on the power line side of the AC transformer.
