Lower or increase pulseaudio volume on all outputs

I'm frequently changing the audio setup of my laptop (sometimes using the built-in jack port, sometimes nothing at all, sometimes using USB headphones, sometimes using the jack port in the dock of my laptop). I'd like to have keyboard shortcuts to lower or increase volume *for all outputs at once*, so it works no matter which audio output is currently active. What's the easiest way to achieve this? I also see that in pavucontrol, I can go above 100%, which is sometimes practical, so if the command was also able to do this, that'd be great. I'm running Debian Testing, kernel 4.9.0-3-amd64, and pulseaudio 10.0.