Total Rubbish!
That is why all the top DAC and Server MFRS are adopting fiber.
Fiber optic is fine for TV ampnd midfi , quality Ethernet cables and a good linear power supply from Linear Tube Audio from the modem- Router combo is sonically superior with a Quality Ethernet hub , is sonically far superior but will cost over $5k to do it . I am speaking in absolute terms fiber optic sounds respectable though ,