Billy. Does exactly that. Using it for 15 years on many different machines. https://www.sheepfriends.com/index-page=billy.html Beside its extreme simplicity I like ...

Oh yeah, it also has one killer feature: you can manage your music collection using the desktop version of Winamp and also transfer songs from your desktop player to your phone using a WiFi connection ...

I switched to Winamp to sync my iPod, and everything's been working awesome. Only one problem. I updated some tracks with lyrics using Tagscan, deleted them from the iPod, then retransferred them.