After upgrading to firmware 9.02 I still get a pop with the amp set to Brit Pre, Boutique 1 or Boutique 2. It happens on presets created from scratch as well as on V9 factory presets (e.g. 041 Boutique 1, 140 Enumerating Ravens, 223 Rackmount Preamps X2, 235 Basic Brit Pre). USB is not connected. Gate on or off does not matter. Any suggestions what could be wrong?