Is there a disadvantage to copying my file from mp3 to wav for TuneCore?
Yes. The file will become much larger with no increase in quality. It will increase to the size of a regular CD file but will still sound like a lossy MP3. If you are targeting iTunes then at some stage in the future it will need to be converted by smebody to the iTunes Store standard which is 256 k AAC. AAC is another lossy format and it will potentially undergo additional quality loss and sound worse than the original mp3 (another lossy format) which lost quality from the original sound.
Note: Certain sound formats such as MP3 and AAC are small because certain tricks were done to make the files smaller. In doing so some sound features are lost = lossy format, and every time you convert you lose more. Some formats reproduce the original CD quality = lossless. AIFF & WAV = lossless, MP3 and AAC = lossy. Going from lossy to lossless there is no loss but also no recovery of original loss made when producing the original lossy file.
By WAV they are specifying a format but are assuming you are getting your track off a CD with CD quality. Since this isn't your source quality then there's no point in using WAV. It would just be misleading since they would assume the WAV was from a CD, and any vendor would probably just re-encode it to some lossy format such as AAC or MP3 for selling anyway.
I don't know iPods. I don't know if they can record in full-auality AIFF or, as I suspect is more likely, they record in some compressed format (AAC, MP3). If it was there as AIFF then you can do a direct AIFF to WAV encode to make TuneCore happy and no quality loss.
Anyway, I'd really look into getting a high quality copy of your track if you're trying to market this.
On TuneCore. I don't know. When I started typing TuneCore into my search engine it started autofilling the line and the second item on the list was "TuneScore scam". Obviously there are some unhappy people out there, but I'll leave you to read those.
