When the Naked is set to its maximum position, the volume should be exactly the same as the bypassed signal.
Please do the following test to check if your Biscuit is ok :
– Switch the BYPASS on and send a signal to Biscuit
– Turn the DRIVE pot up until you see the BYPASS switch lit from green to orange quite often
– Turn the DRESSED pot to its minimum position and NAKED to max
– Check if you still have volume drops between Bypass and not
Please let me know if it works.