For any type of headphone or speaker I’m an advocate for burn-in. Many people don’t believe in it, many people do. I’ve heard significant differences, sometimes night and day, with certain speakers and headphones.
In this, I’m talking about mechanical burn-in, in which drivers “settle” their frequency reproduction. I usually do 72 to 96 hours of white/pink noises and full frequency sweeps at around 50% volume. Or I go through 4 or 5 iPod batteries with music in shuffle at 60% volume. And I go there to listen every 24h. Some people talk of brain burn-in, which obviously also occurs. Your brain tends to get accustomed to a certain tonality, a certain timbre. But the mechanical part is very true. At least for me and many others.
Since you’ve already had them a while, mechanical burn-in has occurred while you listened to music. You may EQ them more to your taste but you won’t change the fundamentals mentioned above.
I’m using the Azla Crystal (in Large) and I’m loving it. I also agree that the amount of bass is correct and enough for me.