I'm guessing since you listen to dubstep that you should find a track that is ripped to FLAC or similar. Newer music tends to have been recorded such that they are high fidelity... but since dubstep is produced almost entirely by computer (and hence, isn't as likely to exhibit the same kind of realistic, atmospheric feel as an orchestral performance), you may want to find something that is produced by an artist using "traditional" recording methods like a studio or whatever.
Basically, what I'm saying is, find newer music, recorded after 2000 (usually, the more recent, the better, as in: more likely to be recorded using high fidelity equipment), in >320 kbps if lossy. You'll understand a clear difference if you were to use a 128 kbps MP3 and compare it to the same track using 320 kbps or better. Once you've established that you can clearly hear the difference on the same headphone, compare between headphones and see if you can't pick up finer details or more clarity in the sound production through your DT770 using the Cmoy BB.
You should still hear a difference, although ultimately, unless you have proper amplification for your high-end cans, you'll either barely notice a difference or you'll not hear a difference at all. It may even be possible that you'll hear it worse, as might be the case for when people have a particularly difficult to drive set of headphones (such as your DT770). While the reasons for the same track to sound worse are many and varied, it's a start.