The LX7 does have an internal power supply, different from a lot of their "Live" series which had external boxes. However, I know of several theatres in the UK that used LX7s for many years without problems. Frankly the record was better than my Spirit Live 4 with the external box--I spent more time than I like to admit soldering new electrolytics onto the rather fiddly board in the PS. It's a good thing I liked the mixer or I wouldn't have bothered!