A co-worker gave me a printout of an online article last week about hearing. It said it's pretty easy to turn up headphones louder than you'd turn up an amp. Why? Not sure, but you can easily damage you hearing because you can't "feel" the sound of a regular amp. I play through headphones every night and I try to be careful to keep the volume reasonable.
You actually answered it. Since you can't "feel" the sound in headphones at lower volumes you tend to turn up the volume until you do "feel" it then it is too late for your ears.
This is only semi-related but I used to work security for concerts way back when and I still have a ringing in my ears from it. Bands like Ted Nugent, Guns-n-Roses, Goo Goo Dolls all did wonders for my hearing. I wasn't smart enough then to where ear plugs...plus all those times I would crank my stereo or walkman....
Another suggestion is something I do...I have a V-Amp 2 effects processer. I keep my amp turned up to 8 and the effects processor is what I use to control the volume. I find I can keep the volume down very low and still have the quality effects...
