I suggest you to use iPhone Transfer for Mac, it's a tool which can transfer music from Mac to iPhone easily. You can follow the way below to see how it works.
Step 1. Download iPhone Transfer for Mac to Mac
Step 2. Install iPhone Transfer for Mac and launch it, then connect your iPhone to the Mac
Step 3. Preview the music and them transfer them from Mac to iPhone
Just in 3 simple ways, how to transfer music from Mac to iPhone becomes an issue which is easily to be solved. iPhone Transfer for Mac can not only transfer music, but also photos, videos and contacts etc. And what's more, Mac is just one of its service objects, iPhone Transfer has Windows version, too. At the same time, iPhone 4/4s/5/5s/5c/6/6 Plus and iPod are also available. If you are interested in it, don't hesitate to try on it.