The SU9920 is a signal processor that is used to improve the presence and liveliness of audio signals. For the unit's signal processing, a combination of a dynamics filter and a phase delay algorithm are used conjunctively to create the functionality of the SU9920. The principle is based around the speed that frequencies can travel. Depending on the frequency, the speed will vary. For example, lower frequencies will travel more slowly than higher frequencies. This can lead to phase issues during sound reproduction. The SU9920 will use phase delay to make those frequencies travel at the same speed. This, effectively, will make it so that all of the processed signal's frequencies reach your ears at the same time, giving your music a stronger, fuller sound.