I have always wanted an actual WAV quality sound to be the POST beep, just like on any Mac. But is it possible, at all?

I guess it would require some kind of custom BIOS using a built-in sound chip on the logic board. I doubt it could be actually implemented in place of the POST beep, but then again I have seen some rather advanced BIOSes, such as those on Asus boards like mine. If not during the POST, then perhaps as part of the OS bootup. I couldn't see Windows doing it, but perhaps in some mod for Linux.