From Longman Dictionary of Contemporary Englishpersonal stereoˌpersonal ˈstereo noun [countable] TCRa small MP3 player, CD player, or radio which you carry around with you and listen to through small headphones
Examples from the Corpus
personal stereo• If you have ever switched on a personal stereo full blast, you will have some idea what it feels like.• Do not wear a personal stereo headset so that you are unaware if some one comes up behind you.• That was more like a cumbersome personal stereo.• She was the woman who discovered the personal stereo in the early nineties. 