Do you know what could be causing a low humming sound from a 6505+ head? It's not very noticeable from a few feet away, but when I'm a couple of feet away, I can hear it. It gets worse as I turn the gain up, so I'm wondering if maybe this is just part of having a high gain amp or maybe I need new tubes? Does it with all guitars/cables, and pedals. Doesn't do it on the clean channel or with very little gain.
It could be a lot of different things. Most likely, you're changing the angle of the pick a little bit, allowing it to "catch" on the strings a little more instead of gliding over them smoothly. It could also be your hand is drifting closer to the bridge, which will make your tone twangier. I change my pick angle and where I pick in relation to the bridge depending on what tone I want; and depending on whether I'm tremelo picking chords or just single strings. Hope that helps!