As for the input and output interfaces, iPhone only has headphone output, which generally uses the standard 3.5mm jack, which is the most common headphone jack on the market. If you want to connect to a power amplifier, you can only connect to karaoke. The microphone interface, but the microphone interface is 5.5mm, so you need to buy a small to large audio cable, that is, one end has a 3.5mm jack and the other end has a 5.5mm jack. If you can't find one for sale, just buy a cable with 3.5mm jacks on both ends, and then buy a small-to-large adapter. The electronics market sells accessories, and all the bosses know it. After buying it, plug the smaller end into the headphones and the larger end into the microphone jack of the amplifier, adjust the channels, and you're ready to use.