Goldwave 4.26 under CrossOver Office 4.2 is quite good. I am running Ubuntu Linux 5.04 "Hoary Hedgehog". Goldwave installed without any real problems. I have been able to open, play and modify .wav and .mp3 files with this version. The only area I have had any real problems with is recording. In Gnome I had to open the volume control applet and play around with the different sound source volume controls. When recording there are often issues related to the display. Most of the time the display didn't match the recording so it was difficult to judge what the recording would produce if anything. Once I set the recording levels and decided not to worry about the display I was able to record high quality sound files.
I have not found any software under Linux which will allow you to exercise as much control over sound files as this app will. All of the other apps I have encountered were simply not mature enough to do the job. I use this software mostly to convert my old tapes and records to MP3 format so I can take them in my car with me. This software is great for that because of the cue points you can have it create automatically to split larger files into smaller ones. Now I just start a tape playing and start up sound-recorder and let it go. I can then split the file easily into smaller chunks using the white noise in between tracks without having to manually find, crop and save each track. This software is great for that and it does this nicely in CrossOver Office.