@audiosens I just replaced my pre-amp with an EAR 864. It used to sound rather forward and lacked good depth. Also, some recordings sounded great but so many others had that congealed sound. I replaced the cheap ass glass fuse with an SR blue I had lying around but was told by a friend, sounded mediocre (he didn’t use it more than10 minutes).
Immediately, it sounded superior. A little dark but oh, what separation of instruments and big tonality. It got better over 15 hours. Then it became too bright from 15 to 20 hours. I just let the pre-amp stay on for 48 hours more. That was it. Just like in my amps with the SR Black (took 72 hours to sound good), the fuse just needs on-time with no signal and steadily improves/stabilizes. Sounds fantastic.
I intend to replace my EAR 890 amp with the SR purple now. It already sounds great with a cheap ass glass fuse. How much better will it sound with an SR purple (or even a $25 audiophile ceramic fuse like an Acme or Gustard). That’s rhetorical.
Without this fuse upgrade, I was ready to chuck the pre-amp and try an EAR 912. Wow! what a great improvement from this fuse.