I had this problem too when I first hooked my Empeg up to my Meridian system. What it turned out to be was that the Empeg outputs 1v on the RCA outputs. When I configured the Meridian system to accept 1v inputs...it works great...although...if I BOOST any of the EQ bands then it does some nasty digital clipping somewhere in the chain... but I'm usually careful to only cut with the EQ, never boost. I used it for a New Years eve party and cranked music all night no problems once I was setup for 1v inputs.

For your system, you may need to get a small voltage matching in-line device to make the line voltage levels match up. Possibly your system at home is 4v, which seems more common. My meridian was set to 2.5v and it was still distorting VERY badly until I set it up for 1v inputs.