Hi, I have just inherited a Marantz pm35 mk2. It's rated at 45w per channel at 8ohm (55w at 4ohm) and thought I'd give it a run through my Zensor 5 speakers in case it's better than my similar period Denon 720. However the speakers are rated at 6ohm impedance. Is it 'safe' to run the Marantz with the Zensors? Is the amp underpowered for them (room size is 4mx3m).