I do think there is a tiny advantage placing them sideways, I am running the M1 Mk2's this way. Even tho you say bass is non directional the futher away from ear level or the level of the tweeter, you put the bass speaker the more stranger it would get?? Its possition within the room, and distance from the tweeter that affects it. I dont know, it just seems a bit more logical to place your monitors sideways if you can