Yes, that works well! The AUX input of the stereo system has the red and white cinch connections. If you have a record player with a magnetic pick-up, you must connect an equaliser preamplifier between the record player and the stereo system. I use the HAMA PA 506 Hama PA 506 (Entry).
Please note that good quality audio cables are essential, otherwise the result will be disappointing. I use the Goobay Plus Cinch - Cinch Kabel Goobay Plus Cinch - Cinch Kabel (1.50m, Premium, Cinch) and am very satisfied with it.