Yeah, I know I can allow the user to adjust the volume, but I also know the kind of folks who'll be using this, and they'll do things like max out the volume and connect 4 ohm speakers in series thinking two speakers will be louder than one. Or worse yet connect them in parallel across their 7w amp rated for 4 ohm speakers and either blow the amp or overheat it or cause distortion, I'm not really sure which.
I just don't want them to either blow their speaker or think it sounds crappy and blame it on me. 
And if they do blame it on me I want to understand what's going on well enough to explain to them why it's not working the way they want it to.