I've heard the Ultra more than a few times. Output is definitely comparable in the usable range, but it lacks serious grunt down low. By low, I mean pretty low too, as this thing will get into the teens in room, just not with the same authority as the Ultra. IMO, the Empire has a somewhat cleaner sound being sealed (I've only heard the Ultra in 16 and 20Hz tune, not sealed). Aside from the amp issue I had that they took care of, I have zero complaints about the Empire. I am very pleased with it for music.