L-550 integrated amplifier combines Class A design with Luxman’s patented Duo-Beta circuitry, which optimizes open loop performance and eliminates DC offset. This enables engineers to minimize negativfeedback and achieve extremely wide bandwidth and low Transient Intermodulation Distortion. Duo-Beta leads to Duo-Beta/S, ONDF (Only Distortion Negative Feedback) and today’s ONDF 4.0.