The quality of the power supply has become one of the most important components of a high-end music system. Because of the switchable power supplies of computers, TV sets, microwave ovens or light dimmers high-frequency noise and DC components are super- imposed on the mains supply. At times the standing DC component is big enough to cause hum in normally quiet transformers. Also, the sound coming from a music system may change depending on the time of day or day of the week, suddenly becoming colorless and weaker. For the dynamic suppression of superimposed DC components Burmester has developed a patented switching circuitry. Additionally, the 948 contains top-quality filters against high-frequency noise.