??? Fuse UpGrade??What Size???

I can vouch for the Synergistic fuses, I was skeptical, put one orange in my amp... Then I had to do every fuse, my preamp, my DAC, my streamer now all have SR fuses. Some really good snake oil that adds warmth, analog, real sounding performance value.

Now for the rest of my life I'll have to always buy these things because I couldn't have a 50¢ cheap fuse be the weak link in any component going forward... 

I'd use a pure copper penny to get the best sound. Pre 1982. (pssst, fuses make ZERO) difference in sound).

Can a McIntosh 2301 Mono amplifier fuse be upgraded?

@emergingsoul -

     There’s a fuse holder, next to the 2301’s IEC PC socket, on the top/rear of that amp.

                            Yes: that fuse can be easily upgraded.

     Two fuses also reside on a Printed Circuit board, within the amp.

      Those are harder to get to and you'd have to experiment with them, as regards any sonic benefit.

                                               Happy listening!