It may be an iPhone. Some of its circuits are short circuited. If it gets hot, don't use it. ! iPhone headphone jack hot cause:
1: If this phenomenon occurs when the earphone does not play sound, that is, the earphone is not working, it is basically understood that the earphone hole of the mixer has additional current output.
2: If the headset volume becomes smaller when the sound is played at the same time, that is, the effective motion amplitude of the diaphragm becomes smaller (is blocked), it can be basically identified that the headset output amplifier circuit of the mixer has a serious fault, mixed with the direct current signal.