These are not my words, but they ring true to me:
"An AC line fuse on the primary side of the power transformer is not going to make any audible difference, since the AC will be stepped down, rectified and smoothed into DC, then regulated before it reaches any amplification circuitry."
And if that's not convincing, let's ask the experts at ARS. Where all audiophiles turn for unbiased opinions (come on now, every now and then they get it right)
" I do not say that any so called audiophile fuses are any better, I will say that if the fuse is not used directly in the audio circuit path, (ie it is used in the incoming mains ac power) it is highly unlikely to have any audible improvement for even the most golden of golden ears and I would place some money on those bets any day of the week."
For what it's worth, I bought a high end fuse for my amp after reading about them on this very site. And the difference in sound was absolutely zero. The only sound I heard was my $150 flying out the window. My ears not golden enough? Maybe. There are just some things that defy logic, and this is one of them. If you are hearing a difference, then that's all that matters. Cheers.