I have a DA5ES as a pre/pro, running through 2 Parasound 1205's, with Klipsch RS all around and an SVS sub. My fronts and center are passively bi-amped. I get to demo a pair of Linn Espek fronts and a Trikan center. My question is about the now mismatched ohms rating. The Klipsch's are 8 ohms speakers and the Linn's are 4 ohms. I will still have the 4 RS3 II's as surrounds. I think there is a switch on the back of the DA5ES to select 4 or 8 ohms. Which should I choose? Or does it matter if the DA5ES is used just as a pre/pro? Thanks.