@captaindidactic Your report that bypsass (putting a jumper or slug in) resulted in much better sound is totally consistent with my experience.
I don't think audiophile fuses can ever approach the performance of a jumper. Fuses have to blow and to blow they have to have a significant resistance and low melting point. Jumpers don't have to blow.
The real answer is replace your fuse with a breaker, thus the SDFB which will outperform any audiophile fuse.
Jerry