Nope, you want to plug the RCA's into the RCA's, no soldering necessary. The empeg has high level RCA's, but they're still not capable of driving anything more than a small pair of headphones. If your amp really only takes 1V RCA's, it may clip if you turn the empeg all the way up. The solution to this is to not turn it up that far. It's a voltage/resistance/current thing, which someone else can probably explain better than me.

Matthew