> MP3 320 KBPS, FLAC, ATRAC. It all sounds pretty much the same to my ears.

FLAC and ATRAC should be sonically identical to what the original CD puts out. Those formats are lossless. They compress the CD info but they don't lose any of it. They're like audio ZIP files. All the info is there and it all gets played back. Anyone who claims to hear a difference is high on something and wouldn't be able to pass a blind test to identify which is which.

The MP3 is "lossy". Some information does get discarded in order to save space. The goal is to discard information that you wouldn't really hear anyway. And at 320 kpbs, that goal is easily met. You shouldn't hear any difference between an MP3 at that bitrate and the CD it was ripped from. MAYBE on a state of the art sound system some people could hear a tiny difference if they knew what to listen for. I doubt I'm one of those people.

The difference between CDs and LPs, on the other hand, ANYONE can hear. We all heard it in the 80s and made the switch as soon as we could afford to. The only problem in the early days was the recording engineers didn't always know how to use the new technology. They'd put the mics too close or something. I've got a recording of Vaughan-Williams' oboe concerto that is both breathtaking and maddening. The sound is crystal clear... and I can hear every single click and clack of the oboe's keys. It's like I'm sitting on stage instead of a few rows back in the audience.