Best way to hook up Denafrips

I have ordered a Gaia and a Terminator Plus and want to know the best way to hook up. I feel a little confused. On USB A to B is the B I2S and what cable would you suggest? Audioquest has several grades of cable but one dealer said it might not be money well spent by buying closer to the top of the line as opposed to getting a good power cord.  Thanks in advance.