After months of tweaking, cause that's what I like to do. I checked my hum balance today. no I'm not obsessed with checking it. I have .006mv. What may have led to the improvment are Shugang Treasure 2A3-Z tubes, Magnequest nickle iron and Munford silver/oil 3.3uF caps. Which may get changed out for 5.6uF in the not to distant future.