sony xo-D501 heavy bass amplifier only 12k only for serious buyers Sony XO-D501 Compact Hi-Fi Stereo System, a collectible rack system from the late 1980s or early 1990s. Components: It features a quartz-lock digital tuner, a double auto-reverse cassette deck, and an amplifier with a 5-band graphic equalizer. Power: The system is rated for high peak music power output, often cited around 550W P.M.P.O. Features: Includes features such as surround sound capabilities and random preset tuning.