The loudest thing I've ever witnessed was definitely Motorhead on the "Motorhead" tour - their "first" tour round a load of smaller provincial venues - Cambridge in my case - they supported BOC with an earlier lineup but that was not the same... never seen them post Fast Eddie...
Probably my fave Slade gig was during their second coming - a Christmas show at the Hammersmith Odeon (approx 1980) with Noddy resplendant in red suit and beard for a certain song - as a general rule they did not play it and at the bigger shows made the audience do it, even in summer...
When I saw them in '74 at Wembley it was duing the peak of their career, but Wembley was a cavern and they were dots - Home supported them for that gig - NME awards show... great show, but...