Just read on another forum where the people who sell Isoclean fuses told the owner of an Audio Research VT100 MKII to go to a 7 amp fuse as they didn't have any at 6.25 amps.
Anyone considering ever changing a fuse for any reason should never change the fuse to another value than is specified by the manufacturer. The fuse is there to protect other parts of the circuit and a higher value fuse can cause much more damage than would have normally happened. Just a heads up on anyone thinking of trying these fuses. In my opinion this is very poor ethics on the part of the Isoclean people just to make a few bucks.