⭕ For sale a RARE Mark Levinson No. 333 Audiophile Dual Monaural Power Amp. These amps are legendary for sound and build quality. he No.333 is one in a series of Mark Levinson stereo power amplifiers. Extensive cosmetic alterations, internal structural changes, and new circuit designs make it quite different from the models that preceded it. These design refinements are part of Madrigal Audio Laboratories flagship amplifier.