The volume is adjusted to several tens of percent, and the sound is the best.

If the volume of the player is adjusted to 70-80% and the volume of the stereo is adjusted to 30-40%, the volume is the best at this time, because the sound emitted by the player and the stereo will be distorted at full load or near full load (90- 100%), but it will not be distorted at 70-80%, so that the timbre and timbre of the high and low tones can be fully exerted.