I've got a CD of Elgar conducting his own violin and cello concertos, recorded in 1928 and 1932. The CD was produced in 1989, and there's quite a bit of surface noise from the shellac discs it was mastered from. I wonder whether it might not be worth running that CD through Audacity's click removal algorithm; possibly whatever they had in 1989 wasn't as good at the job as the one that comes with Audacity...