Hi. I have a big and growing music library. My iPhone can hold all of it as of now, but I am running out of space and I will soon have more music then space. Right now I have a mixture of .m4as and .mp3s. I have started converting all my music to .mp3s trying to get rid of all the .m4as, but I am wondering if there is a format that will make smaller files at the same bitrate and frequency as my .mp3s. I don't want my music to sound all tinny, but I don't need CD or .wav quality either. I tried an experiment of taking some .m4as and .mp3s and converted the .mp3s to .m4as without changing bitrate or frequency and converting the .m4as to .mp3s without changing the bitrate or frequency. I was trying to figure out what files would come out smaller, but sometimes the .mp3s came out smaller and sometimes the .m4as came out smaller so I was confused. I could not figure out which one would truly be smaller. I did not bother testing a third format, because I figured what happened with the first 2 formats I tested would happen again with the third format. That is, I would end up with mixed results. I figured there would be people who would know more about file formats then me, so that's why I am asking here.