Should i up the rating say from a 4 amp to 5 amp?That’s been debated extensively in the "Synergistic Red Fuse" thread, with disagreement even among the technically-oriented people. Given that detailed information defining the technical parameters and blow characteristics of the SR and most other audiophile-oriented fuses is not available, and given also that the answer may very well depend on the unspecified surge currents ("inrush currents") that briefly occur when a component is turned on (which in turn will vary widely in both magnitude and duration among different components), there is probably no way to provide a definitive answer.
But FWIW the opinion I expressed in the SR thread was basically that the various reports of failures that have been posted (by at least seven people in the past year or two) suggest that a 5 amp SR fuse may actually be closer in its blow characteristics to a 4 amp "standard" fuse than a 4 amp SR fuse would be. Which if true would say that the rating that is used should be higher than the rating of the stock fuse. Others disagree with that philosophy, however.
Regards,
-- Al
P.S: Dave, thanks for the nice words. Best to you.