Distance and delay should be the same thing. They're related by the speed of sound.

I've discovered that auto-cal is a good start but you have to trust your ears. My Denon mic and my meter couldn't, for some reason, account for the fact that I have a large staircase beside my right M80 and QS8 but my ears could. I actually ended up tweaking all the channel levels to my liking because I found that setting them all to match the same SPL at my sweet spot simply wasn't giving me the right experience.

You should put your A1400 on the box that has the lowest parasitic impedance to ground .