A fuse on the power input only has two potential modes of interference
with
the sound: (a) Limit the power so that it can't produce enough juice at
the
end, or (b) Generate some power-line distortion that's so bad the power
supply can't deal with it. If the first mode were true, then the fuse
would
melt--that's its job! The second mode is unfeasible, because an inch-long
piece of wire simply isn't complex enough or different enough to generate
some magical distortion which a paperclip or silver-solder joint is less
susceptible to. It's simply not possible, and anyone who claims otherwise
is
either deluded or trying to sell you snake oil.

It's conceivable that he had a poor connection to his original fuse, which
improved step by step as he substituted other things. If so, the thing to
do is clean the contacts and reinstall the original fuse (or rather an
electrically equivalent replacement, since if the original fuse was getting
old, it may have increased in resistance).