Steve, a few words about clipping, tube compression, ear damage, etc. please??

Steve, I was reading the archives last night and I came across this old statement that you made with regard to someone turning up their Scott 299 too loud. You basically said to remember that at high volume levels, you are basically creating a tube compressor and that although tube distortion sounds good, it IS clipping and can damage your ears. I got to thinking about that and it's one of the main reasons I decided to pick up that Fisher 202-C, reasoning that with an extra 17 wpc over my HK A500, I should be able to stay clean at louder levels. I'm wondering how to avoid hurting my ears? If I turn these babies up and it sounds good, how am I going to know how loud is too loud? How loud IS too loud? Should I get a decibel meter and just go by that rating or is it the clipping I should be worried about? I think that my HK will clip before it gets to a level that I would perceive as being too loud. Do I need to hook up an oscilloscopes to find the approximate clipping threshold and avoid that region? Is it the clipping itself that is bad for the ears or is it that in combination with excessive volume? I would be grateful if you could elaborate on this and help many of us save our ears so that we can appreciate your fine mastering as long as possible!