I'll be short : I was very disappointed when I listened to the PAA1-Pro the first time. I found bloated bass, harsh highs and a typical mainstream V-shaped sound signature. So, I began a hundred hour burn-in and retry it... Nothing changed a lot. Maybe the highs became less harsh but still not what I would call pleasant to my ears. I put them away a time and come back to them after two weeks. Still nothing changed. So, I take my time and passed few weeks with them, switching between different sources like : Sansa Fuze, iPod Classic, Teclast X3, SMSL...