Shop name: Chong Qing Shuo Yue Ke Ji You Xian Gong Si Power supply: Dual AC15V to 28V (AC requires rectification and filtering) or DC18V to 40V, recommended DC35V. (Note: A dual 35V transformer provides approximately DC35V. Recommended transformer: dual 26V / 200W toroidal transformer, rectified voltage about DC35V.) Note: Battery power is not supported. Transformer: Dual-channel transformer should be no less than 200W. Single power transformer should be no less than 100W. Power supply rectifier and filter: Two-channel filtering should be no less than 40,000 uF; rectifier bridge should be rated for more than 25A. Output: Maximum output 85W. Negative feedback: Capable of driving passive speakers. Product is a single channel without rectifier circuit. For stereo setup, two boards are required. Net weight: 30g Heatsink: Required based on supply voltage and output power. (Heatsink not included.) Audible noise: None Midpoint voltage: Less than 1mV Color: Black Material: Plastic Dimensions: 50 x 35 x 25mm Package Contents: 1 x Audio Amplifier Board Note: Onboard IC amplifier is new. The product is pre-welded and tested as a fully functional board. Package includes only the items listed above. Other accessories are not included. Note: Due to lighting and display differences, the item color may vary slightly from the images. Measurement error allowed is +/- 1-3cm.