Something I never get to say: It does what it claims to do in one click and one drag. It has no frills, no extra clutter, it's exactly what I went looking for. Only thing I'd like is a couple more shortcut buttons (like the 100% one) for 200% or 150%.

Update: To anyone who says it isn't changing, make sure that you're on the tab that you want to make louder/softer and that the media is actually playing when you move the slider.