Mixed reality (MR) in standalone headsets has many advantages over other types of devices. With the recent appearance of the Passthrough of Oculus Quest 2, new possibilities open up. This work details the features of the current Passthrough and how its potential was harnessed and its drawbacks minimized for developing a satisfying MR experience. It has been applied to learning to play the piano as a use case. A total of 33 piano students participated in a study to compare participants' interpretation outcomes and subjective experience when using a MR application for learning piano with two visualization modes (border lines on all the keys (Wireframe) vs. solid color hiding the real keys (Solid)). The two visualization modes provided a satisfying experience. Even thoughthere were no significant differences in the analyzed variables, the students preferred the Solid mode, indicating that short-distance Passthrough limitations should be minimized in application development.