1. The device has reserved DC interface, audio input AUX interface and headphone output port, and is compatible with XH2.54 interface, providing rich product interfaces. Users can freely choose according to their needs.The TYPE-C interface can be used for power supply/USB sound card. For the QCC5125 model, the official software can also be connected through the USB interface to operate the EQ in the internal DSP, which is especially suitable for senior enthusiasts with software foundation. 2. The onboard antenna can reach a transmission distance of 50 meters in an open environment, without external antenna. If it is installed in a metal shell, in order to avoid signal shielding, you can purchase an external antenna by yourself, and reserve the IPEX1 generation antenna seat for installation. 3. The device is equipped with an I2S output interface,which can be connected to an amplifier with I2S input function.At the same time,a key expansion interface is reserved to realize the functions of switching between up and down songs,volume adjustment/playing,pausing,etc.which is highly extensible.Design a "cancel Bluetooth connection button".When an unknown Bluetooth device is maliciously connected,long press the button for 3 seconds to cancel the connection of the unknown Bluetooth device. 4. QCC5125+PCM5102A chipset realizes lossless transmission and decoding, perfectly showing the dynamics and details of the sound. The high frequency is delicate and burr-free, the mid-range is round, and the low frequency is powerful and elastic.Its excellent parameter performance includes:dynamic range 112dB, signal-to-noise ratio 112dB, distortion -93dB. Demonstrates unparalleled sound quality performance. Such excellent performance allows you to deeply feel the improvement in sound quality. 5. Assembly instructions: The shell needs to be assembled by yourself, and theUSB cable and audio cable are not included in the delivery package, but the following accessories will be included:One XH