I have searched the archives and there isn't much discussion on this. I am not seeking for a debate on this. I would just like to know what format do you guys usually use when listening to music on your portable gear. Basically I have compared both FLAC and MP3-320 on both my low-end headphone gear and home audio rig. There is a difference in sound quality between FLAC and MP3-320 when music was played on the home audio system, not a night a day difference but noticeable enough to my ears. When played through my headphones, my ears could not detect any difference between the two formats. For this reason I am inclined to use MP3-320 for my portable gear. I would like to seek the experience from folks who use higher-end gear. Do you usually listen to MP3-320 or FLAC? Any thoughts or advice would be appreciated.