Best non-destructive free wav editing solution

Hey there,
I am interested to burn an Audio CD. This will be a compilation having as source, wav files. I am interested to mix some of them using custom curve crossfade or no fading effects.

I know that some burning software (like Nero for example) have a built in option called crossfade with previous track, but the result will involve a fade in/out as well.

Having this project in mind, what is your recommendation in order to preserve the native quality of the wav tracks? Saving the compiled files (wav as well) could come with loss of quality? how can I check taking in consideration the fact that the resulted files will be at different duration, CD index, etc.

I’ve tried Nero SoundTrax but no so sure about the quality.