Yea once it's compressed into an mp3 file converting it back to WAV won't make it sound any better. If you're not making a CD or using them for something that doesn't have mp3 playback I'd suggest keeping it the same.
I wish I knew this 2 years ago when I converted all of my files to ALAC because I thought it made them sound better lol. I'm glad I'm done with iPods lol.
Lol, I know I won't get better sounding music just by doing the conversion, can't create something from nothing/crap. But I wanted to know if some of the software out there would make it worse (not sure the means or algo they use to do the conversion). I ask because I swear I think the last time I did the conversion the mp3s sounded better then the converted wav. I think I used winamp. Why am I doing this? Because I don't want to use USB to my dac.