FWIW, with Quad 63's I listened to them with the axis passing just behind my head. Maybe 5 degrees less than pointed straight at my head.
One of the reasons I liked this was not just because of the direct signal, but in my set up the backwave hit a sidewall before it hit the back wall (behind the speakers) and helped dispurse/diffuse the back wave. But each room and set up is different. Just fiddle around.
BTW don't forget in setting them up that they can be placed much closer to side walls because of a far more restricted off axis radiation pattern/amplitude, with toe in towards the listening position you just don't have near the first reflection point issues from the side walls as you do with cone speakers.
