I used the so40 system for over a year in a permanent instalation for live sound re-inforcement. I had 2 of them to use in a karaoke system in a lounge. They worked perfectly! I found that when paired with an sm57 or sm58, I got about the sweetest vocals I could ever ask for. They are fairly rugger, too, so when used with the sure mics, they make about the most road worthy setup going. the signal response was exceptional, but I did have to keep them away from large steel posts when they got more than about 50 feet away, which wasn't very often. I'm hoping to add a couple of the so40s to my current system. Hope this helps!
