I've seen DT live three times. The first two were in smaller indoor venues in Chicago, in fact it may have been the Aragon both times, and they sounded effing fantastic.
The last time I saw them they were co-headlining with Megadeth for Gigantour at the First Midwest Bank Amphitheater. They sounded horrible there. I don't know why but it seems like only the headliners ever sound good there, and that's not always a guarantee.
Apparently they must still consider a co-headliner to be an opening act and they hit the "make it sound crappy" knob on the soundboard for them.
I heard that about the Gigantour. That's why I'm worried about this tour, though I still will go.