Though most modern music is noise-free, anything you record from old LPs or cassette tapes is bound to have clicks, pops, or hiss that you'll want to remove--without creating a muffled-sounding mess. That's where BIAS Inc's SoundSoap 2 steps in.
Unlike the $499 Soundsoap 2 Pro, which only works as a VST plugin for professional recording apps such as Presonus's Studio One, Soundsoap 2 comes as both a plugin and a standalone program. It lacks the Pro version's high degree of tweakability, featuring only and noise and click slider, an enhance slider (to add back dynamics that may have been lost) a few sliders and buttons.
The true test of any audio restoration software is how well it removes noise without affecting the dynamic range, i.e. removing the high frequencies. It helps tremendously if there are periods of musical silence that still contain the noise. The program can create a noise profile from these--always record your tapes or LPs with plenty of lead time before the songs and edit out afterwards.
I used SoundSoap 2 on a horrendously noisy, pop-ridden 78 rpm recording my operatically-inclined father sent my mother when he was flying in the Pacific in WWII. The results were fantastic. No other consumer-level program removes as much noise while still leaving the material recognizable.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.
--Jon L. Jacobi