Many musicians are bothered by signal loss when their pedal chains get too long. Plug your guitar into the FAT preamp, then out to your pedal chain, and everything will be right again.
Kick the pedal on for a clean boost. When the boost is on, use the LOW and HIGH knobs to shape your tone.
The BOOST knob gives you up to 26dB of extra volume. The CUT button enables a low cut filter (cuts the 200Hz frequency).