@audphile1 Even with FMC, ethernet cable quality still matters, your experience illustrates that. Using your best ethernet cable closest to dac makes sense. Upgrade all your ethernet and be prepared for further gains. Upgrading from Supra and various other ethernet to AQ Vodka was well worth it for me.
Further gains with generic FMC can be had with even better lps, power cords, and connection to power conditioners.