I saw them on the Pyromania Tour in 1984. Ex-Thin Lizzy guitarist Gary Moore was the opening act, he had just released Cooridors of Power album. If you haven't heard that album, check out the track "End of the World" sung by Cream vocalist Jack Bruce. In concert Gary did his own vocals on that song, he's an OK singer. Actually since he's now dead, he's not good.
It was a 3 band show, Krokus who was on the "Head Hunter" Tour was the second act. Between Gary Moore, Krokus and Def Leppard it had to be the loudest show I ever attended. My ears felt dead for 3 days. Def Leppard was amazing and also put on a great show. Part of the volume problem was both Def Leppard and Krokus got the audience to yell at various parts of songs, like one side of the audience against the other. This show was in Savannah, Georgia which only holds 8,000.