Indeed, you do. There are likely some models of Crosley that do not require the use of mains power, but for the part the Crosley is not so well bestowed that it can properly function on batteries alone. If this question is, inversely, asking whether a Crosley turntable needs to be plugged into a stereo and/or speakers, then the answer is no, not necessarily. Most Crosleys will come with inbuilt speakers, meaning that the use of external speakers or a stereo system is not at all necessary, unless you actually want it to sound good.