I started by running a microphone sample, but the biggest problem with a 5:1 system isn't just the EQ... it's also the levels of the various channels to get everything to mesh properly in the middle. The automatic EQ turned the volume of the rear channels up WAY too far and dialed my subwoofer out entirely. The only thing it correctly identified was a hump around the 80Hz cross between my mains and my sub. I kept that and went back to balancing volume levels all around to create the proper sound field. That affected the EQ, so I went back and tweaked EQ, which affected the volume levels and sound field, and so on... It was a series of parallel parking back and forths for a few months, with progressively smaller and smaller corrections until I got it right.
When I got it to work properly with music, I put on a modern movie with low frequency info and it started to shake the walls. I found I had to completely rework the low end, fine tuning the hand off from mains to sub even more. Now, I finally have it completely balanced all around and everything I play through it sounds right. It was a LOT of work. Not at all just setting out a mike and pushing a button.
I have a friend who is a sound mixer for live concerts and I told him about my struggles and he laughed and said "now you know what my life is like!" He said he goes into venues where the theater or amphitheater owners tell him that they had a tech come in with a sampling microphone and flatten the response. But he starts running sound through and finds that it's still all over the map. He said his first job after setting up is correcting the corrections.