The Cayin (TAD) does not have amp inputs. When used with an external pre-amp, you simply connect the pre-amp L&R outputs to one of the inputs on the Cayin (like the aux. input). The "pre-amp" section of the Cayin is actually passive and only has the volume control pot in the circuit. You would simply turn the volume control to max. and theoretically this will pass the signal through to the amp intact.
Enjoy,
TIC
Enjoy,
TIC