The discussion of hiss removal has been done. Not to upset you but all so far do cut into the signals you want to save.

https://www.google.com/#q=audacity+alternatives finds the alternatives, many are free. My son who does some audio work but never deals with hiss because in his world they bring the actors back in for dubbing or rerecording if the tracks are bad. https://en.wikipedia.org/wiki/Dubbing_%28filmmaking%29 covers that.

For music I no longer bother but hit the usual itunes, amazon, etc. to get a fresh cut.