The Circle 25 features a materially superior body. The MDF body has been replaced by delrin, a high-grade engineering polymer. Delrin is stiffer, vastly superior in terms of damping and much denser. The new Circle 25 is 3-kg heavier than its predecessor. The added mass at the base of the structure improves the mechanical stability and damping of the Circle 25, providing the black background within the sound stage on which the instruments and voice place within.