AAC, MP3 128, 192, 256, 320 kbps? Which one do you use, mostly? I've got a ton of CDs to rip. Will be using iTunes. Don't have the best quality earphones or external speakers to justify using lossless formats so lossy will do. Not an audiophile but I would like my music to sound pretty decent. Is there a significant difference in the size of the files for the different bitrates?