For the record, just so there isn't confusion, the actual file format of everything in that archive is WAV. This is to prevent cheating. An easy way to spot the difference between a WAV and an MP3 is to look at a file header. While the format for all of these files is WAV, I saved WAVs from MP3 for the MP3 test. Those files will sound no better than the original MP3. And best of luck to anyone spotting the mixxed files. ;)