I was looking for a modern amplification solution and more, for practicing at home. After some time searching and comparisons, I made the decision to buy this Spark 40. Aesthetically, it looks very good, but maybe a little smaller than I imagined. It has modern facilities for studying such as displaying guitar chords, singing along... It has enough possibilities for formatting the sound, but unfortunately the overall sound is too bassy and the default volume is too loud. In order to help you sing with smart jam, you must not have headphones connected, because the phone's microphone will first record the sound and then find the harmonies. So in the end he is intelligent and not very. However, such a device is worth trying, but it is a bit expensive.