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 sap-4s, JDS Labs cMoy (with the stock opamp) even the Aune T1 but, eventually, I have to admit that I never find them pleasant to my ears.
 
For me, with the PAA-1 Pro, you get what you paid. It isn't the badest earphone, I listened to, it just mainstream one for 30$ no more no less. Finally, I've found it lacking of confort and i was unable to run with them too. Whatever position, I tried, the keep falling of my ears during my running session.
 
I would thank HSA for the sample but as I said during our mails' exchange, I have to be honest with myself. I didn't like it that much, it isn't bang of the buck for me, just a honest price for those earphones.