1. M18 Mute and Key Button Control Mute control terminal: easily manage the power amplifier board with a dedicated mute function. When muted, the MUTE output is at 3.3V; during playback it stays low. Key Button control: expand your listening options with external resistors and buttons for volume control, including a volume poweroff feature for quick mute or powerdown. 2. Flexible Power Supply for M28 and M38 Power options: both M28 and M38 can be powered via MICRO USB (5V), a 5V power supply, or a 3.7V lithium battery. Recommended for performance (M38): a regulated 5V 2A power supply is advised to achieve sound quality. 3. USB Sound Card Compatibility Plugandplay USB connectivity: connect the module to a computer with a USB cable, enabling the PC to output audio through the module's amplifier. 4. Advanced Technology and Easy Pairing Latest version V4.2: automatic pairing and support for multiple formats including WAV, WMA, FLAC, APE, and MP3 with lossless decoding. Simple device pairing: power on the module and your phone will detect MHM18, MHM28, or MHM38; connect for seamless music playback. Usage scenarios Desktop computer audio upgrade: connect via USB to enable amppowered playback from your computer without additional drivers. Portable or batterypowered setup: power the module from a 3.7V lithium battery for a compact, onthego audio solution, with the option to use a 5V supply for longer sessions. DIY audio projects: use the mute terminal and external button control to implement convenient volume management and quick mute in custom speaker or amplifier builds.