It was a good idea the first time, and it’s a good idea now, although four discs worth of ’70s covers does seem to be pushing things to the saturation point.
For whatever reason, the band’s brand of classic power-trio heavy rock seems to spring into a further dimension when the three members step onto a stage.
Sucking the ’70s succeeds where so many before have failed because the concept encapsulates such a large chunk of space and encourages bands to take chances.