Thanks. Actually I never used any specific burn-in noise, and whenever I felt my headphones need stretching, I just blast Dvorak Symphony No. 9 loud, and the sound usually gets better after a few spins. I never tried balanced mode since all my headphones are either single-sided or Grado, but I have a pair of HE400i on the way, so probably would try a balance on them, though not sure if it's worth it. However I do heard that Pono's balanced mode is very good, and some even compare it to Sony PHA-3, which costs twice as much.