I had a Terminator and now have the Terminator Plus. I found the best input to be the HDMI and use a Denafrips Iris DDC to change USB to I2S. The Terminator 2 has the clock out to sync the DDC and it is worth it, but even without using the clock out the I2S is better than USB. But, I did have a music server with I2S out that was not as good as it's USB, beware not all I2S is good.
The Terminator Plus is better than the original Terminator with any input.