What songs do you use to test for depth?

Ill have to look at that Bass Mechanik track in a spectrum analyzer.

Was using the Wasserman/Warnes track Ballad of a runaway horse to test and I was trying to position the speakers where the bass was even per the Sumiko Masters setup method. I listened to the song on my headphone setup (Wadia 121/Audeze LCD2) and noted the bass notes weren’t the same volume. When I put it in a spectrum analyzer you can see that each bass note is at a different volume.

After that I changed my speaker setup to achieve the levels closest to what I was seeing on the spectrum analyzer.

What are you testing your headphones for? Frequency response etc?