Well I've given up using the Marshall and am using the digitech on its own - it has a chrystal clear sound ( no hum ), but is still too loud for the Mic input - so i've fitted a Pot and a resistor in series in the output leads so i can turn down the volume and prevent any red lining of the studio meters - I can monitor what I'm playing on headphones from the digitech -I can now get a clear recording with equipment I already had to hand.