I've built a headphone amp with vt-25 tubes using a S.E.X. amp as the donor chassis. I get a loud hum in both channels which is drowned out by moderately loud and up levels of music. I've read all the posts here about tracking down hum, and I am perfectly willing to spend the time necessary to reflow all ground connections when I find the time. Is there any significance to the fact that the hum is constant and does not vary with volume setting?
Thanks
Robert Lees