Yes to all of the above. With music machine like ACDC it's much better to have music loud. But importantly, the quality of the sound is greatly enhances. It may just be the quality of the headphones vs normal pinball speakers, or that the mechanical sounds drown out some of the effect sounds, but the sound you get playing is greatly enhanced with the board/phones. You can still have sound on the machine too, or switch it off if you prefer. Not sure there would be such a great difference with other themed machines, but I'm putting one on LOTR so ill let you know.

Thanks for the clarification. Sometimes I wish I could turn off all the noise so I can play and not disturb the wife. My only option is not to play on accasions or get her to put headphones on.

BTW have you even played a game with no sound? You'd think it would be ok but its not. Its a bit like no background music on some movies, they tend to lose their impact etc.