Hi, is it possible to bi-amp with model 1070? I only need a 5.1 system.

This way the 65w/channel is good enough power for L&R (130w/channel).

Thanks
Xavier

highly doubtful.but what you describe is bridging unused channels,also doubtful.

There is a pre-out but not a amp-in on it. So assuming you had speakers you could bi-amp you would still need an external amp even though you have two unused channels. As paintoad said, neither can you bridge channels to get greater output. If you are crossing over to a powered subwoofer and your mains are of typical efficiency then 65w will be more than plenty. If you want to drive your mains full range or they are peculiarly inefficient then you may need more power. Do you know what the efficiency rating of you speakers are? What frequency range do you send to the subwoofer?