Isoclean fuses are sold direct by the distributor, although Isoclean dealers (I am one) can get them. They only make slow blow types because they have found fast blow not to sound acceptable.
Isoclean Fuses
A few months ago I blew the fuses on my venerable Aragon 4004 mkII. I wondered if an Audiophile fuse was available but had never heard of one. The recent edition of Positive Feedback has a review penned by Albert Porter discussing Isoclean audiophile grade fuses. Anyone had experience with these yet?