The materials used in D325MF are of high quality. The sockets are gold-plated, which is more . The large heat sink ensures long-term stable operation, and the large-capacity filter capacitor makes the power supply more stable and the ripple is lower. The power amplifier chip used is ' TPA3255, which can output 300 per channel. The op amp used is NE5532, and the decoding chip is ES9028q2m. In addition to the high-performance microprocessor chip, whether it is an external optical fiber coaxial input, USB disk playback, or Bluetooth playback, the high performance of ES9028q2m can be used to make the details richer and the dynamics more outstanding. The PAUSE button on the front of the machine can be paused by pressing it shortly, and can enter song in Bluetooth and USB modes by pressing it long. The INPUT input switch button can switch the input by pressing it shortly, and can enter the previous song in Bluetooth and USB modes by pressing it long. When a USB flash drive is inserted, the machine automatically switch to USB mode and directly. The USB file system supports FAT32 and exFAT. The audio file format supports MP3, WMA, APE, FLAC, and WAV. The highest bit rate supports 16BIT48KHz. It can play general lossless formats. Instructions: 1. The D325MF output can only be connected to passive speakers, not active speakers and constant voltage speakers. 2. The power amplifier board uses DC24V-48V power supply. The higher the voltage, the greater the power, but it cannot exceed 48V, otherwise the amplifier burn out. The power plug is 5.5 x 2.5, positive inside and negative outside.<br><br>3. The negative poles of the left and right channels of the amplifier output cannot be connected together, otherwise it cause the amplifier to burn out. 4. The Bluetooth connection needs to be switched to the display screen to display "BT" before searching for Bluetooth. The name is "" and it can be connected. Product model: D325MF Input method: biaxial, coaxial, optical fiber, USB, Bluetooth Amplifier chip: TPA3255 x 1 Bluetooth version: Bluetooth 5.0 Frequency response range: 20-20KHz Power supply: 24V-48V Decoding chip: ES9028q2m USB playback format: MP3, WMA, APE, FLAC, WAV/16BIT 44.1K-48K Output power: 300W x 2/4, measured at 48V Total harmonic distortion: 0.05% Applicable speakers: 10W-300W 4 ohms 8 ohms 16 ohms Bluetooth transmission distance: 10 meters Protection mechanism: Power reverse connection protection, short circuit protection, self-recovery overheating protection Size:178mm x 123mm x 42mm Color: Black Material: Aluminum Alloy<br><br>Package Contents: 1 * Decoding and playback digital amplifier (Power cord not included) 1 * Remote control<br><br>Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.