Yeah. If you had really read my post before you'd know that I already know about the $vol and /volume variables/commands.
Also, the volume controls built into the computer don't go as high as the settings that you can do in mIRC. You can set the volume level a bit higher in mIRC than what you can in the normal volume controls. Yes, I know you could turn up your volume on the speakers too, but this would be for when you don't want the volume to be louder for anything else, but want the mIRC volume to be louder so you could hear it over the other things going on.