Setting up some M2s in another room and want to run speaker wires from one side of house to other where the amp is.

What gauge would you recommend? Thanks.

12

you better braid 3 piece of 0 awg silver wire to get the best sound at that distance.

either that, or 12awg will be enough =)

GN, study the article and table here , which indicate that a 14gauge or heavier cord should be used.