I own a SWR SM-400S that is running at very low output for some reason. With the volume @ 10 it is still fairly quiet and burned up both of the tweeters in my two Aguilar GS112's (in church). I took it to a service tech and they resoldered here an there and gave it back with the same problem ($200 charge). I took it back to them and they say it is fine and testing at about 220watts bridged @ 4ohms. I stated that it is a 500 watt head. According to them that is a peak figure and not RMS. Is that true? I've noticed that most other amps are rated at RMS. It still makes no sense since I used to run the volume at 2 or 3 and it was plenty loud. Any opinions or suggestions?