I think the kemper powerhead at full volume is to much for one speakers.probably the sound peaks damage my two speakers.now i turn the power amp boost to higher settings,and all is ok¡¡¡
??? Did you read the post from CK just 3 posts above yours?
By using Power Amp Boost your speakers are even more in danger - it's just a simple 'power boost' no compression/limiter or whatever involved.