Our bassist uses an early 1970s V4 head, through an Ampeg 1x15. Pretty close to your set-up, right? Anyway, after a year or so of great bass tone, the thing now sounds pretty bad. The low-end is really distorted and nasty. it sounds good if he's playing quietly, but at at any respectable volume level it just sounds very fuzzy. All the depth and warmth is gone.
You think he needs to just get new power tubes? Other thoughts/suggestions? Anyone else experience similar V4 problems