A rare pair of Quad II Mono-Block Tube Power Amplifiers. They are in excellent condition, with only minor scratches and dents that do not affect sound quality. The original Quad II monoblock amplifier is a 15-watt RMS tube amplifier known for its low distortion (<0.1% at 700Hz), using 2 x EF86, 2 x KT66, and 1 x GZ32 tubes.