Periodic replacement of Audio Grade Fuses?

I do not suggest that this manufacturer is correct, however fuses do wear, depending on how close to their rating they are used. Typical fast blow fuses are spec'd to carry the full current rating continuously (well almost, for more than 1 hr), and burn at 2x the current rating in about 120 seconds. If you operate a 1 amp fuse at 1 amp current for, say 30 min, you will notice the element deforming as it is close to melting. For most common fuses that don't have precious metal fuse links, this deformation occurs at high temperature and will induce oxidation in the fuse link, potentially increasing it's resistance. However, one would think that a manufacturer using gold, Pt, Ir or other PM wire would not see this effect.

And of course, to see this effect the fuse needs to run close to its rating, or even above routinely. For conservatively designed equipment running well below the fuse ratings, I doubt if the fuse "wear" would be descernable.

A common application where fuse wear is really noticable is in many older German cars (BMW, VW, Mercedes) where those open construction ceramic "bullet" fuses were common. After many years, you will see twisted and distorted elements, even though the fuse has not "blown".

Thanks for all of your responses. I plan on keeping these fuses in my amps for as long as they function. The note on their card does make me wonder how many customers do actually replace every 6 to 12 months though.

I wouldn't bother changing upgraded fuses.

Think of it this way.

However much they "might" degrade overtime, they will still be sounding better than a stock fuse that "might" be degrading over the same period of time time.

The emphasis on "might".

Until some misadventure or faulty component trips the fuse and it blows, I wouldn't bother changing them.

Is this a paradigm shift?
We now have something that doesn't sound better after a break in period?

I prefer to think my Supremes are sounding better with age.

Fuses...I worked for a well-known electronics retailer years ago. Guys would come in and say, "Hey dude, my receiver keeps blowin' fuses, should I put in a bigger fuse?" Naah, just stick a penny in there instead. I guess for high-end stuff, you should use a .9999 fine gold bullion coin.

Old 6eyes, my take is that you no longer are employed with the well known electronics retailer?

Perhaps you should have suggested that the " guys" invest in better electronics that won't blow fuses, and perhaps you would still be working for that well known electronics retailer.