Half Bridge resonant SMPS capable of delivering 200W continuous and 280W peak power. It uses open loop half bridge resonant topology and the output voltage is within +5 and -10% of the nominal voltage when the current draw is varying from 0-100%. The main advantage is lower size and cost compared with a similar regulated SMPS and better efficiency compared with the regulated SMPS's due to the fact that the transformer is driven with almost 50% duty cycle all the time, and the current through the switches has sinusoidal shape, and there are no output inductors. The SMPS features overcurrent protection which limit the output current at about 160% of the maximum power, about 320W. This power supply is suitable for both class AB and class D/T amplifiers, which have the PSRR greater or at least 54dB. Target applications for this power supply unit include the TDA8920 or LM3886 based amplifiers for the +-27V version, TA2022 based amplifiers or LM3886 amplifiers for the +-30V version, TDA8950 or UCD180 amplifiers for the +-40V version. The size of the board is 100x50mm and the maximum height from the PCB is 26mm, bringing the total height including safety distance under the PCB below 35mm, allowing to be installed in 1RU cases or any other low-profile enclosure with proper clearance under the PCB. This is the smallest dedicated power supply for audio amplifiers on the market with the highest power density per size and volume.