The least expensive fuse upgrade is flipping all existing fuses in the system around - one fuse at a time - and listening to how the direction of each fuse affects the sound. Even for fuses that have been in the system a very long time. There's a 50 percent chance that a given fuse was originally inserted in the "right" direction.
Upgrading Fuses
Have a Audio Research Ref 3 and am considering upgrading the fuses but I am a little skeptical. Would like to hear from people who have try this. Hard to believe that fuses can make a substantial difference like the manufacturers claim. All advice appreciated.