The sound quality from a mid-range CD system can be improved dramatically by placing a glass of carbonated mineral water equidistant from each speaker and at a 45 degree angle from the position of the amplifier. The shape of the glass is not important, but it must contain 285 ml of liquid to achieve maximum effect. French mineral water works best, although some systems prefer Scottish mineral water. Do not under any circumstances use still mineral water as this will degrade sound quality by introducing top-end resonance. A slice of lemon may counteract this effect if carbonated water is not available.