I just found this today:
"The World’s Loudest Band, Manowar Kicks It Up a Notch with Meyer Sound and Westfalen Sound
Epic heavy metal band Manowar secured a place in the Guinness World Records during the 1990s as the loudest band in the world, and sheer volume has remained an integral part of the Manowar concert experience. The band’s technical rider specifies a minimum unweighted SPL of 126dB at FOH position, a feat few sound systems can handle and still maintain the sound quality.
So when, during the sound check at the second annual Magic Circle Festival in Bad Arolsen, Germany, Manowar achieved levels in excess of 139dB through Westfalen Sound GmbH’s powerful Meyer Sound MILO