I discovered that my fiio a-1 amp makes the 7506 better in a way I can't describe.

Even though they are easy to drive just a tiny bit cleaner amp helps.

I also discovered that both my phone and sony MP3 player have messed up headphone jacks

(This took me like three tries to write this because my computer crashed firefox that many times(I think it was that I need to close fourm and reopen it again)