Sound Soap 2 of Bias is superb. I wish I knew about its existence years ago when I was exhaustively cleaning up old discs and badly recorded concerts in order to burn CD and prepare mp3 ... At that time, there existed a solution. I think it was called O'Cedar (like the carpet cleaner !) but costed several thousand dollars and therefore was not meant for individuals... It was consisting of a hardware PCI card (with a sound processor dedicated to cleaning) and an attached software. Not for me ! not for us !
SoundSoap 2 came too late for me ! recording job is practically all done and there's lot of clicks, crakles, hum, rumble on my archives. I hate to think that SoundSoap could have taken them off in a jiffy. Go and have a look at it !
You can download a trial version for your Mac or your PC (nobody's perfect) fully operational for 14 days and if you like it, take $99 out of your pocket and it's yours to enjoy. If you live in Europe, it's not too costly with the conversion rate dollar / euro. It works as a standalone or as a VST or AU plug-in. Although it really does the job, please don't expect an alchemical result ... it betters but can't transform an old 78rpm disc into a luxurious DTS !