Power Cord suggestion(s) for Rogue Cronus Magnum III

I was lent a pair of Nordost power cords Frey (supposedly good) to try....to tell you the truth, I was underwhelmed....very SLIGHT improvement over stock supplied PC.  Consensus seems to be that replacing PC in a system makes the biggest difference over other cords????..My system: Cronus Magnum III - Sonner Legato Dual Speakers - Innuos Zenith server and Ideon Ayazi II DAC. I find the system very revealing.  I'm wondering if I have "tin" ears.  Comments/opinions on a decent pc for the Cronus is appreciated