When I was much younger and had better hearing and MP3 was a new thing, I ripped my CD collection and encoded everything with whatever the state of the art was back then (bladeenc? mp3enc? this was pre-lame). After a while I started hearing artifacts in MP3-encoded music so I did some A/B testing against the original CD the music was encoded from. Turned out those same artifacts were in the CD.
MP3 encoding has matured and improved since then, so whatever degradation there may have been, it's less now. I've only ever used 128Kbps stereo encoding, and I've never been able to detect any difference from the CD in any kind of music. This is with fairly high-quality sound cards, amps, and speakers.
Of course, my high-frequency hearing is pretty much gone now so I sometimes worry that my music collection might sound horrible to anyone with fully functional ears.