PinVol is an open-source Windows program that makes it easier to control the audio volume on a virtual pinball cabinet. PinVol controls the audio volume on your cabinet through software, by adjusting the Windows master line-out volume level
Most cab builders use this approach anyway, because the audio amplifier is usually hidden inside the cabinet, so its volume knob (if it even has one) isn't easily accessible. Some pin cab builders do go to lengths to make the amp's volume knob accessible, though. If you went that route, you can still use PinVol, but you'll want to set your physical volume knob all the way up and then forget it exists from that point on, so that the software has full control over the volume.