I've always read that it's good to decompress mp3s and other compressed formats to wav by a standalone program rather by Nero, which I use for burning. I've done this by using CDex and it has worked without any problems. Sometimes I just drag & drop mp3s in Nero so it decompresses them. I really haven't noticed any differences between these 2 methods but am still skeptical bout the queality.
So, what to use for decompressing? Thank you all!