The preamplifier has two 6.35mm sockets, one RCA (Lotus) socket, input socket and one RCA (Lotus) output socket. It has high and low tone adjustment, gain adjustment, reverberation adjustment, etc. even inexperienced new users can call out satisfactory sound after being familiar with it for a period of time.     The built-in Bluetooth module is used to connect casual clothes. The built-in Bluetooth wireless module no longer restricts the connection distance. High speed Bluetooth transmission supports the connection of most digital products on the market.     Plug in the USB flash disk directly to play music. MP3 audio files can be copied into the USB flash disk and directly inserted into the USB socket next to the display screen Press the move key to switch to the USB flash disk mode, and press the play key to play MP3 music      Excellent sound amplification.     Practical reverberation effect adjustment.     Key Function:     1. Power switch key.     2. 5V Voltage Power Supply Input (Supporting Power Bank Power Supply)     3. Machine Power-on Working Indicator Lamp     4. Audio AV Input (Left and Right Channels)     5. Video Input     6. Audio AV Output (Left and Right Channels)     7. Audio AV Output (Left and Right Channels)     Plug Type: EU Plug, it applies to Indonesia, Germany, France, Spain, Italy and so on. / Plug Type: US Plug, it applies to Canada, India, Mexico, Thailand, Taiwan, the United States, the Philippines and so on.     Colour: white     Material: plastic     Size: 14.6x14x4.5CM          Package Contents:     1 * Host     1 * Plug          Only the above package content, other products are not included.     Note: Light shooting 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.