No, the sound is nice just "for a short moment" prestretch can be good, also can be harm your racket caused the racket grommets and frame sink in badly. So we will use our way done according to our certified stringing method with private tension calculation, this can be better than machine pre-stretching to ensure the string tension drop slower. Note: If you are a current national player or sports school athlete, we have our specialist stringing method to fulfill your need to prevent tension drop and increase control level.