Hello Everyone, 

I bought the Marshall code 100 Head as a second hand after watching the positive reviews of it, and I really liked the sound and its features!

I plugged it to a 1 x 12 Cabinet and it works good except for my big disappointment with the hissing white noise that i was getting even when the master volume knob on the amp is turned all the way down. 

I tried every simple solution that i could come with, including turning off the computer in the room, I tried resetting the Amp to factory settings,  I even installed the new firmware from the marshall website.  but none solved this issue.
Does anyone know the solution for this problem? 

Thank you very much in advance

Hossam Othman