The PX-5S audio/line inputs and dual headphone jacks make this a powerful instrument for teaching, as well as for performance. For those of you using "tracks" as I do, the audio input works great from an MP3 player or computer. However, many people do not know that the line inputs are NOT disabled, that is, the audio input and the line inputs work at the same time. A teacher and a student can use the dual headphone outputs to hear the board. Pre-amped up via a mixer or other device, the line inputs can be used with a mic system to talk to the student as the teaching progresses. For private teaching this is very powerful.