BTW, every now and again I have to plug my powered mixer into some powered speakers. I take the line outs of the mixer, no problem, but of course, you have the power amps in the mixer STILL working away, into no load at all... Few powered mixers allow you to turn down the powered amps without turning down the main line outs, too, and most RCA outs are pre-fader.

So I always carry two dummy plugs to plug into the powered mixer's 'amp in' jacks, which effectively disconnects the power amps from the mixer signal. Now, the amps aren't seeing any signal, and they stay nice and cool, despite still being on...

I know most people know this trick, but if you didn't...

Hope this helps.