In my system, I realized that I would have to do fuse tests separately for each component.
My preferences after warming up QSA fuses (300h continuously), compared to my Orange:
Classe M300 power amp (biamp mid/high). With Yellow, there are not big, but pleasant improvements.
Classe CP-700 pre-amp. There is no winner. I chose Yellow, because I hope that they will not burn here like SR.
Lumin U1 & Paul Hynes SR5 PSU. I am very surprised, but Yellow and Purple did not bring significant changes.
Sotm clock (feeds Esoteric G-01 and D-02 DAC, USBultra, Switches) and USBultra & Paul Hynes SR5 PSU. A strong performance jump with QSA Yellow and then with Purple. Without Purple, life goes out of music. In this place, I will test Red.
PS Audio P10 (feeds SR SX PowerCell). Switching to Yellow has made the biggest contribution to the sound of my system. It is comparable to replacing the USD3000 cable with USD6000. I order Red.