John - normally you're going to have some kind of volume control with whatever you have these or other headsets hooked up to. In my case I have AM/FM, MP3 (seldom used anymore) and a XM radio (used 99.999%) that my headset taps into. Otherwise you could just rig some kind of volume control or potentiometer to your setup and control your volume output.Dale,
Do those attenuate? (& if so; how much?)
Think of these as what you might plug into a Ipod or MP3 player (and such) to give you quality listening in a helmet and motorcycling (which is pretty darn nice when you get used to it or spend lots of hours on a ride).
P.S. But to answer you question on how much - potentially, I can hear quite clearly great sounds at most any speed and have more volume output available if needed. I still can hear what's going on with my motorcycle and traffic around me too, which obviously is important and critical.