You don’t need certain music, or any music at all really. The formula for imaging is as simple as everything must be perfectly symmetrical and equidistant.
This is how I set up mine, and everyone else’s, up to and including the speakers in the Talon Audio room at CES. Which I did after several others spent a couple hours laboring in vain. My method took 20 minutes and everyone was happy.
I am going to skip over the initial steps involved in getting the right frequency balance and go straight to what you asked about, imaging. So there is more to it. But in terms of imaging, this is it!
First we get the speakers perfectly symmetrical and equidistant. To do this we tape a string to the outside bottom edge of the right speaker, wrap it clockwise around the base and over to the left speaker, wrapping around and taping it to the outside edge.
If the speakers are perfectly straight ahead then the bases will be perfectly flush with the string. If they are toed in a little then the inside corner will form a gap with the string. Measure this distance. Change toe of one or the other until this is exactly the same on both sides.
Now measure to the exact middle of the string. Exactly half way between the speakers. Use a framing square to go 90 degrees from this mid point. Place your listening chair somewhere along this line. Not half an inch one way, not 1/4" the other. Exactly on this line.
Sit and listen. Pretty freaking amazing, eh? Now, for the final touches.
Listen for image focus, and stage width. Speakers pointed straight at you will image like a laser, but the stage may not be very wide. Speakers pointed straight ahead will produce a much wider stage, but without much focus. I find the best balance with almost all speakers has them pointed at each shoulder, or converging a little behind me. But that is my preference. May not be yours.
Don’t waste your time with recordings. They are all over the map, and cannot be used for this. There are a lot of awfully confused people out there happy to confuse you as well, because misery loves company. Use string, tape, square, and be happy.