I noticed yesterday that I've got low output on one channel of my ST-120. This has happened twice before — not always in the same channel — and both times replacing the LM334 regulator did the trick. I've ordered a new part, and I'm sure that's the problem this time. It's an easy enough fix, so I don't mind the occasional replacement. But I do wonder if I should be looking for the underlying cause. The unit does got hot, and it may be that the problem is triggered by long sessions where the amp is on all day and gets hotter than usual. But it sits on a top shelf in free air, so maybe that's not the issue. Any ideas?