HiFi tuning fuses, some benefits help

I had to describe the improvement as, "More organic". Not in any way, "colored". Rather simply more, "alive". ie: More wood from a Double Bass, rosin on the bow, skin from drums, breath and chest resonance on vocals, etc. Subtleties for certain, but worth it(If you're into realism). Try them in the AC main of your amp first. If you don't realize any audible improvements there; They may not be for you or your system. Ignore any "Placedo-Effect" pronouncers that might pop up here. They seem to forget that, should one expect no difference; they probably won't hear one(Reverse-Placebo). Then again; most that knock these fuses, haven't tried them in the first place.

My Mains are modded Cary tubed monoblocks, and the improvements I mentioned were most noticeable in that app. I've also installed them in my modded TransNova 9505 woofer amp, but installed IXYS soft recovery FREDs at the same time, so I can't honestly quantify their impact or contribution to the speed and definition I gained there.

Depending on your view of a power amplifier's operation, the AC line fuse can be considered directly in the signal path. The voltage/current taken from the wall/AC line is converted to DC, stored in filter capacitors and is connected to your speakers via the output devices(be they tubes or transistors). Those are simply switches/valves that modulate(YES- the correct term) the current flow to your speakers as directed by the musical signal, which proceeded from the preamp/source section of the system(which IS NOT connected to the speakers). That same power supply also provides voltage to the input and driver stages of the amp. That's why cleaning up your AC power, or making even simple mods to a power supply can yield major changes in the sound of a power amplifier.