I I have a 4 moth old Mark V that has a distint hiss/hum/buzz in all modes of channel two whenever the gain is above 12 oclock or the volumn is above 11 oclock. To a lesser degree I have the same thing happening in channel. I only noticed this about a month ago although I have to say that I normally don't have the channel volumn or the main output set above 11 oclock. Is this normal and if not suggestions would be helpful?