Download link: https://files.letasoft.com/dl/SoundBoosterSetup.exe
After installation, launch the app, play any sound by any another program (for example, i opened ReactOS_LogOn.wav by mplay32 and enabled repeat). Then, click on the tray icon and try to enable/disable or move the volume bar up or down in appeared dialog.
When you do this, in w2k3, the volume changes to the set value, and sound becames louder and distorted, in ros it does not. The volume is still not more than 100%. See attached videos and debug log.
Tested with d0632b0 (0.4.10-dev-584), in VirtualBox 5.1.38 with AC97 driver installed from Rapps.