Just what are WAV files? Actually they are pretty complicated files but for our purposes they can be considered uncompressed music files. In most cases a WAV file extracted from a CD is exactly "CD quality". For more information on WAV files this link is a good starting point
We need the files to be in WAV format because that's what the freeware program dvda-author accepts. CDs are recorded at 44.1khz sampling rate and have 16 bits resolution. This is exactly one of the WAV formats that dvda-author accepts so that's what we use.
You can convert many formats to WAV but you will have varying results. Typically CD to WAV is excellent no matter how you do it. Another common misconception is that mp3 and other formats are better than WAV/CD since they are "newer". This is usually not true at all. mp3 is a "lossy" compression. That basically means that data (quality) is lost when you convert something to mp3. Many times the emphasis is on making files very small in size. This generally means lower sound quality. For things like portable music players this may be fine but for inside the TL you will hear just how amazingly bad most mp3 files sound. I find most mp3s un-listenable on any high quality sound system. Once converted to WAV they can sound even worse. One to the best mp3 encoders is Lame. If you are interested in mp3 then check it out. I find if you encode at 192K minimum then the songs are suitable for background music, casual listening and non-critical listening in the car.
Certainly experiment with converting various non-CD files to WAV. All to often, though, I find that they will have audible problems. Many times they sound a bit like they are coming through a garden hose.
The topic of how to convert various files to WAV will be covered on the "How to convert to WAV files" page