My system had a dull and lacking treble. Because the IEC plug did not use much force to connect I changed the IEC and Schuko for a Rhodium type of lowest price level. I reused the Olflex because it is shielded. Compared to the original price level of € 30 it is now a € 100 investment.
Treble is back and the noise floor has dropped, resulting in an upgraded image that is of higher value than the investment.
(Keep the shield only connected on the Schuko side)