If you decide to use GoldWave you will be able to play, edit, mix and restore audio files.
You can add effects like reverberation, fades, noise reduction, echoes,...
One of the features which distinguishes it from the rest is that it can record from any input device like cassette, radio, cd or microphone. While the file is being played it displays several images on screen.
Maybe you find it difficult the first time due to the high number of features offered and the lot of icons shown on screen, but after one or two sessions, you'll master it.
Gold Wave supports wav, mp3, ogg, aiff, au, vox, mat, snd, voc, raw and more formats of up to 4GB, which will be able to be converted from/into all of them.
In addition if you make a mistake while editing the audio file you can restore it and go back to the initial point.
The trial version only allows you to execute 150 commands each time the program is run.