Shure's SM58 is an advanced heart-shaped directional vocal microphone. This kind of microphone is specially designed for professional singing amplification and studio recording, emphasizing the saturation and clarity of sound. Output level (at 1000 Hz): -54.5dBV/pa (1.85mV). This voltage cannot be directly connected to the power amplifier, and the level is too low. Especially the civil power amplifier at home, the magnification is lower than that of professional power amplifier, and the sound can't come out. Generally, such a microphone needs to be connected to a mixer to be used. Or add a microphone amplifier (not what you said! ), and then access the power amplifier.