【Introduction】 ZK-502M AMP is a mini Bluetooth AMP smaller than a card, its peak output power can reach 50W+50W, wide voltage input: 5-24V, you can easily buy a matching DC power supply. 【Friendly Design】this AMP protection board is printed with connection icons, allowing you to easily connect to each port without reading the manual. 【It Has Many Functions In A Small Size】 This AMP has three input methods, their input sequence is USB mode→AUX mode→Bluetooth mode. You can directly connect to the computer through the USB interface without a driver, you can also connect to the playback device through the AUX 3.5mm interface, and finally, you can also connect to the mobile phone through the Bluetooth mode. 【What Kind Of Speakers Are Connected To It? Active Speakers? Passive Speakers?】 There is no doubt that both can be connected. When you connect passive speakers, this AMP is a Bluetooth power amplifier; when you connect active speakers, this AMP is equivalent to a Bluetooth receiver. It should be noted that two types of speakers cannot be connected at the same time. You need to choose one type of speakers. Tip: adequate output power is required when the audio input is sufficient and the power supply voltage/current is sufficient, the relative power will be higher. Different impedance horns will have different output power.In the case of sufficient voltage and current, the larger the impedance horn, the smaller the relative sound power, please pay attention! Note: The power amplifier board needs to be assembled by yourself, please rest assured that the assembly is very easy.