1. Volume and timbre

First, use your fingers to play evenly from the highest key (the rightmost key), then play down several keys one by one and listen. Listen to whether the sound produced by the piano is bright and whether it satisfies your preference for timbre.

2. Is the pronunciation even and coherent?

That is, listen carefully to see if there is a sudden increase or decrease in the sound of adjacent keys. If there are no big or small changes in the sound, it means that this is a piano with even and coherent pronunciation. It can also be concluded that the movement of this piano is better adjusted.

3. Open the top cover of the piano first so that the sound of the piano can be released more widely. Then play the keys one by one from one end of the keys again. While playing the keys, listen carefully to see if there is any sand, noise, or mute in each note. If this happens.

4. Touch

When you play a good piano, the keys feel comfortable to your fingers (good touch). When you play the piano, you don’t feel that the keys are too heavy or strenuous, nor do you feel that the keys are too heavy. It's too light to use force. At the same time, I feel that when my fingers touch the keys and leave the keys, the keys can immediately fall and rise back to the original position, and the rise and fall are sensitive and fast.

5. Pedal

If you step on the right pedal, the piano sound will continue after your fingers leave the keys; if you step on the middle or left pedal, the volume will weaken. The middle pedal can also be moved to the left after being depressed, so the pedal function of the piano is complete. When stepping on the pedal, in addition to listening to the changes in sound identification, you should also observe whether each pedal moves up and down sensitively and whether there is any obvious noise when moving.

Reference: Baidu Encyclopedia-Piano