Is this the Fast Track USB or the Fast Track Pro? Both apparently have a "mix" control. From the Fast Track Pro's manual:
"When the knob is turned fully counter-clockwise (the IN position), only the input signals are heard at the outputs.
When the knob is turned fully clockwise (the PB position), only the output signal from your DAW is heard at the outputs.
Any point between the IN and PB positions will give you a mix of both inputs.
The real advantage of the Mix knob is that it enables you to monitor your live inputs in real time as you’re recording them, while also monitoring the existing tracks coming from your DAW, as well as allowing you to control the relative levels of both sources. When you do this, be sure to mute the inputs on the tracks you’re recording. Otherwise, you’ll hear the direct signal AND the return signal from
You might want to check this out.