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

Fuses are important. I wouldn't vary from factory spec. 

@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!

Can a McIntosh 2301 Mono amplifier fuse be upgraded?

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

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... 

IME the Vera-Fi Audio SDFB outperforms any aftermarket fuse on the market. Many excellent reviews here & elsewhere. Email Mark with any questions. He's very responsive. 

I recently upgraded my fuses for my Shindo Mr T,Aqua LinQ transporter and Weiss 501 MK2 for the Pink fuses and after experimenting with the right direction and between 100-200 burn in time,I can hear a very noticeable difference with the soundstage(,wider and higher),Instrments and voices are more detailed and airy and the overall sound is more live. I also recently bought a Rel S510 sub and Wow! It was probably my biggest upgrade. I know adding a second sub would complete the 20% on the 80 % upgrade but I live in a condo with neighbours downstairs so 1 is satisfying for me, should have done this years ago.

One is 20 mm ,one is 32 mm, you can see if it looks small or longer

and if fast blow always go 1 size up I have had fuses go in fast blow fuses on startup why ? The cheap stock fuses can vary up to 20%  

The Cable Company has them on sale.  

I would call SimAudio (Moon) tech support to get their opinion/advice.  I've received helpful advice from them on my Moon 390 set-up.

Go with a 6 amp fuse Fast blow. SR fuses had a history of blowing on inrush current startup if you went with factory size. 

Let it burn in for a week and then switch the direction. If it wasn't in the optimal direction, you should hear a very noticeable difference. If it gets worse, well switch it back. I tend to oversize the fuse... thicker wire. 

@jastralfu ,WilCo...

@freediver keep us updated on the outcome.  I would be interested if you notice any difference.  I swapped in a Purple Fuse and did notice improvement, wasn’t night and day but there seemed to be a wider deeper soundstage and improved imaging.  Could all be in my head but I don’t think so.

Sweet..I did not know the AG designation related to the physical size..Thanks much..

As per 240i manual, page 25; you need a large AG Size (6.3x32mm) Fast Blow - 4 Amp fuse.