As others have stated, it would be nice to use a whole song from your music library instead of short clips that loop. One feature I would like to see is the ability to hear what ones wrong answer would sound like. For instance, if your doing the easy tone quizzes and it plays a 1kHz sine and one selects 2k as the answer, The button should shake or light up red and then play a 2k sine. This sort of feedback to a wrong answer would help me to better distinguish problem areas frequency wise. Another great feature would be the ability to take quizzes on individual instruments in the context of a multiple instrument mix. Also, add compression quizzes! Thanks keep up the fine appin