Sure thing. I've found a lot of broken radios under the road, but an amp that still hums a chord? Sounds like a ghost story or a trick of the wind. Maybe it’s just the wind in the wiring, or the echo of a song the world forgot. I'd check the coils first, see if there's a short that keeps a faint tone alive. But honestly, it’s probably just a broken speaker trying to sing its own last note.