When it comes to audio formats you have two basic types, Lossy and Lossless. Lossy formats are the most common. A lossy format is a file that compresses the information by throwing out bits it deems unnecessary. While much smaller in file size, lossy formats tend to detract from the quality of the music. Some common lossy file types are: MP3, OggVorbis, WMA, AIFF, Musepack, AAC, and AU. Lossless formats tend to be much larger in size, but they retain all of the information found in the original source (ie: taper recording, soundboard). Some common lossless formats include: FLAC, SHN, APE, WavPack, OptimFrog, and uncompressed WAV. For the purpose of trading/archiving live music you want to have the best sound quality possible, so lossless is preferable. In order to use lossless formats, you may need to download the appropriate software. FLAC -Free Lossless Audio Codec SHN -Shortened APE -Monkey's Audio WavPack OptimFROG To learn about SHN go here. To learn about FLAC go here. To learn about APE go here. To learn about WavPack go here. To learn about OptimFROG go here (again) look to the left and click on Features. If you want to jump right in, this is a good place to start. More to come....