Noise was in both channels. The background noise does disappear when I disconnect the input cables, but reappears if I tap on the amp. The noise appears after reaching a certain level on the volume pot and continues as you turn the knob higher though it does vary in intensity.
I tried removing and reseating the tubes, but this did not help. My tubes will not seat tightly/securely in either socket & there is always wiggle room. I've also noticed that the pins of both tubes are not straight, but appear to be bend a bit outwards.
background noise does decrease when I unplug the power supply from my laptop & it disappears when I plug into my tablet instead, but I still get noise from tapping on the amp. I tried adding a ground loop isolator, but background noise still present. I've also noticed noise in the amp from cable movement with three different rca cables and my headphone cables.
what should I do? =(