I had a time when I listened to CDs that were ripped and then compressed to 128kbps MP3. One day I had the CD and just listened to it straight on the computer through headphones and was blown away by how much I was missing on the MP3. My take is 192kbps MP3 is a lot better and 320kbps is basically transparent.
I got a really great set of Yamaha speakers at our reuse center and, similarly, found a whole new world in some recordings (everything by the Super Furry Animals except their first album) but then found others (anything by Foreigner) sounded just the same as they always did on FM radio.