Originally Posted by: KasperowThanks a lot. It clears up most of my questions. One more thing, though. Does the change in sound when Tubes need to be changed happen overnight or does it happen gradually throughout the tube's entire life-span?

It can happen both ways! Generally, there is a gradual change. But less occasionally they go quickly or all at once!

But you shouldn't spend time worrying about it. It's one of those things that happens when it happens.