Why VGA has no sound, HDMI has sound.

Because the audio down line is not available.

The answer here is yes.

VGA is a video transmission port, which can only transmit video signals, but does not have the function of transmitting audio. HDMI has audio transmission function, and it is a digital signal. Because it is a digital signal, video and audio can be played normally as long as the cable is plugged correctly.

As for the problem that Nai's audio add-drop cable can't be used. In fact, the seller misled you This branch cable is actually used to plug in the power amplifier. It belongs to the output, that is to say, the audio analog signal is output from the TV to the power amplifier, and then connected to the speaker. Moreover, since the output is an analog signal, it is directly related to the output power. The notebook computer itself is a low-power electrical appliance, so it will be a little difficult for ordinary notebooks to push headphones with 32 Ω impedance. It is basically impossible to push the speaker of the TV set.