Synergistic Red Fuse ...

The only reason fuse sound is discussed now is there's a  relative yardstick for comparison. What ever level of sound quality provided with a stock fuse the premium fuses are so much improved, you cannot ignore the vast difference. There's a reason the response to this thread has been overwhelming positive by so many people. Just use them and listen, their impact is self evident. 
Charles, 

This is not the first time I’ve heard about synergistic research fuses blowing like this, Almarg’s post is spot on, you see, I’ve never said to anyone here on this thread before, but I have talked to audiophiles about the red fuse since their conception into the marketplace, I also have personally spoken to Ted Deny-founder-designer of nearly all product’s there at synergistic research, as I recall, Ted told me to go slightly higher value on the fuses on the phone, his reasoning was exactly what Almarg posted, I never had a reason to divulge this information before, everyone was enjoying their products without no remorse till now, I will also add that most audiophile’s likely can not get  Ted Deny on the phone, I was very fortunate to do so, the entire reason I spoke to Ted was reported fuses blowing a couple years back, so I’ve known about this for quite awhile.

My REF250 specification is a 7A Slo-Blo but since SR RED doesn't offer that size, so been using a 6.3A Slo-Blo.    Now waiting for my 5 SR BLACK from theCableCo.    Hmm!

Jon, it seems you could pin the problem down for both SR and Ayre by getting all four versions of the ,25A Littlefield fuses for next to nothing and see what blows and what doesn't. If none blow, then SR probably has anot issue.. If some do and some don't then SR and/or Ayre would know how to be more specific about their products.

Since you're without fault, someone owes you restitution, and the tests would help make your case and assign probable cause.

As for the SR Black, my results were so obvious that I've ordered one for an old Classe CA-300 that I'm giving to my new-son-in-law just to give him a better product even though he's no audiophile.  Curious that we've seen so few theories on what is happening electrically.

Maybe lesson learned is Slo-Blo has larger tolerance so safer to roll than a Fast-Blo unless one is willing to roll the dice.

Another thought is audiophile fuses is anything not from the manufacturer.   A Bussmann is definitely a safer bet than one from Ace Hardware with unknown origin.  In Audiophile world, both are non audiophile fuses.