Aftermarket fuse to tame a bright system?

I took possession yesterday of a pair of Audio Magic Masterpiece M2’s to grace the Audion Mk3 monoblocs. These fuses have been just the ticket for the last bit of settling down of the Cornwall 4’s. They get a soft grip on the treble and high mids without lessening detail at all. Even though they are nowhere near break-in yet it is already quite obvious that they are a perfect match for my set-up. First thing noticed was that diction of the sung word was quite a bit more intelligible. This may be because instrument separation is handled better which then de-clutters the music. The music is also less in your face but with no diminution of musical information - more relaxed, more natural sounding. This is as close a sound to my tube set-up as I have ever gotten with a SS system.

I am just starting out - more later.

No. 

Helomac..maybe true, try. 

I like Fat and Flat. Whatever that means 2 all.

Fuses have a standards-based rating. Manufacturers of electronics rely on these standards to protect their equipment. You can rely on industrial suppliers like Bussmann or Littelfuse or Eaton to deliver product according to the accepted standards.

One option is solderable fuses. I use them in the power supply for my DIY phono/pre, and there seems to be an audible difference between the solderable fuses and the cartridge fuses. IMO

I’m an ignorant man, and I prefer to use industrial suppliers when I can. YMMV