Once I mistakenly listened to my ER-4S/TA combo at 100% volume. I wasn't paying attention, and instead of turning the volume down to 0% I turned it up all the way. When the music started I nearly jumped out of my skin.
I turned the TA off, turned the volume back down correctly and waited 'bout 5 minutes to be sure my ears wern't acting funny before resuming normal listening. With my Panasonic SL-SW860 CDP and a typical CD (Dire Straits Brothers in Arms) I'll have the volume on the TA turned up about 1/4 to 1/2 an inch rotation past 0%. If I turn it up 'bout 33% of the way with my SR-80's while not on my head I can feel the bass in the housing... and can hear them just fine several rooms away.