Lightly used in a smoke and pet free home. Over 150 watts per channel (300 watts of stereo power), this stereo amplifier offers superb musical clarity and plenty of power in one compact chassis. Utilizing the finest quality parts, and entirely hand built by experienced craftsmen, the ST-150 represents our pinnacle in stereo amplifier design. The noted VTL quick clean musical sound and exceptional bass punch is delivered here by the 6550C tubes. Exceptionally well suited to triode operation, yet they are also very quick and clean in tetrode mode, these VTL amplifiers are well-suited to smaller electrostatic panels and dynamic speakers not requiring high current. For commanding performances on the midrange and clarity on the top, VTL wins hands down. In triode mode, the amps are best suited to speakers with an efficiency of 92dB/1W/1m or higher. Try these designs as a great sounding alternative to single-ended triode designs.