fuse damage

I think installing a single fuse in, say, a pre-amp, would be worth the $50 price, even if it were not returnable. Installing eight of them in a power amp running eight output power tubes, at a cost of $400 (!), maybe not! But if one can audition them with a money-back guarantee, why not? I would insure the tubes have no shorts before doing so, that's for sure!

a fuse that does its job can not make a system fail,. a fuses only purpose is to protect the unit.
Keep in mind that it is not only a matter of value but there are fast and slow type fuses, this is very important and should always be specified by the manufacturer

I have tons of experience with fuses a steel fuse has 7x more resistance then a Silver fuse ,a standard steel fuse can vary in  accuracy over 15% which is a lot .
A Hifi tunjng fuses for example is accurate within 1%. This is why many times 
A fuse would pop is exactly the same depending how close the MFG goes with a fuse. I usually go up slightly if possible if fuse blows with aftermarket fuse.

In no way will a Hifi tunjng fuses damage a Amplifier. Any proper built piece of electronics should have a minimum 20-25% over voltage protection built into it 
For protection. Gryphon is a veryoung good product. Go with the fuse the recommend sonicly after about 75 hours thd fuse will be runin inner detail as well as low level detail will be improved.