Allow increasing audio volume past 100% with modifier key

**Would it be possible to allow the volume buttons (or maybe the slider in the menu bar) to bump the volume past 100% by pressing a modifier key at the same time**?

For example, have vol+ max out at 100%, but allow alt+vol+ to go past that?

#### Background

I'm running elementaryOS on the ThinkPad X230, which is a nice hardware, but the built-in speaker is a little underwhelming. Normally, I can use headphones which work fine, but sometimes I need the built-in speakers. I have noticed that in the Settings, I can allow the output volume to exceed 100%, which works fine. However, even after allowing the volume to exceed 100%, it's not possible to do so with the volume buttons on my keyboard, or with the volume control in the menu bar (from what I can tell).

#### Prior Art

While I can't do this on my MacBook, macOS allows modifiers to be used while using the volume buttons. On there, option+shift+vol+ can be used to step in smaller increments. I don't know how of if any other distros handle this.

#### Pledge

If you get this working, I will donate $5. I know this is not a lot (I'm a student), but maybe other people who would like to see this also want to chip in?