Initial project - upgrade stock to SR Black in Ayre AX-5 amp - was a two-parter...
First, replaced half the fuses (mis-informed on quantity so originally ordered only half what was needed and had to place a 2nd order after getting the amp opened up and realizing).
Long story short, before having all SR in the system I was concerned, things just seemed off in a lot of ways. Not worth getting into since it didn't last, but a somewhat interesting lesson in that, it seems important to go "all SR" (or at least, "all the same" whatever that may be).
Once I got all SR fuses (8 total so no trivial investment), and after one change in direction of installation (yes, this seemed to make a difference) things started to turn around. And with around 70+ hours burn-in, things started improving dramatically.
Now, with substantial hours in and all-SR Black fuses in the amp, here's what my ears hear (forgive my lack of audiophile vocabulary, I'll just describe it as best I can):
- Improved instrument separation, placement, and 3-dimensionality
- Perception of more immediacy and "smack/oomph"
- Lower, tighter, punchier bass
- Overall just a better sense of musicality
- I feel there was a very, very subtle loss of realism in instrument/vocal texture.
The improvements, with possible exception of bass improvements, I would not say are profound, but I would say more than subtle. They are a matter of improving on the already excellent sonic quality of the amp, in nice, noticeable - but not earth-shattering - ways. The change in bass seems the most dramatic.
I'm not an electronics engineer (although I am an engineer by training/trade) so I have little concept why the above would be the case, but I do have pretty good ears and have been a musician for 40 years, pro at times, so I trust that I'm hearing a difference, and that the difference is an improvement overall.
Whether an investment in upgraded fuses is worth it is a pretty individual thing, dependent I imagine on how much your particular system benefits from a specific brand/model of fuse and your budget. I had a very positive experience with Hifi Tuning Supreme in my last Ayre amp so tried this, and I'm happy with the (in this case rather large) investment.
I've ordered SR Black fuses for my DAC and transport now, and looking forward to hearing what differences they may make.
At some point, I will buy a set of the Hifi Supremes to compare, since I liked what they did in the past. But for now, I'm quite happy with the difference the SR Black fuses make in my amp.