Software that provide feedback on music performance are being increasingly used by music students to support their daily practice. The dominant piano performance evaluation models are based on metrics such as playing correct notes and global tempo. However, these metrics are often limited in capturing expressive aspects of performance, which can be seen through slight variations a performer chooses to employ in their playing. In order to capture some of these variations, we propose a web application that serves to compare the user's playing to that of professional recordings of the same piece. The users playing is plotted in real time on a tempo-volume graph, alongside performances by great pianists such as Rubinstein and Horowitz. We then give this application to music students and from the feedback we receive, determine in what kind of live performance feedback will be useful to pianists.