Best Compression Format For Music

I know the comp media supports many different music formats. Which gives the best compromise between size and music quality. I'm going to start and compress all my CDs so I can setup an SD card and sort the album artwork but I don't want to loose too much of the quality. I have some low bit rate MP3 files and you can really hear where the music has been clipped by the compression.

I PC am rather than Mac

All my digital music is mp3 in variable bit rate and is near CD quality. If coding yourself at a constant bitrate then a minimum value should be 128 but 192 better still. Using a variable bit rate is the best way with 128 being the minimum value, and that roughly works out at 1mb file size per minute of track. Most music you get from iTunes is variable bit rate with 192kb being the minimum.

I use Variable Bit Rate wma files. I'd love to use FLAC but the unit does not support that. Most of my wma tracks are around 300-350 kbps.

I use DBPoweramp on my PC to convert my FLAC music to wma.