Let the amp break in for a while and let us know if the tube noise goes away or persists. If your voltages are within spec the transformer should be fine and perhaps just needs its mounting nuts tightened up a bit.
Thank you, I have been using it with my speakers and headphones. It seems to have settled in, I looked at the voltages again and they are all about normal including point 4. The line noise isn't audible from my speakers but there is a slight noise through my headphones in one channel that follows the tube arrangement, so I think it must be that.
