Hey guys. I have fiio k5 amp and im looking for an upgrade to something much better. Im willing to spend 400-600$. My headphones are: bd dt770 80ohm, hifiman he400i and will have m1060 soon. So maybe i would consider buying amp with balanced out. I was thinking about fostex hp a4bl or aune s6. Maybe somebody have tried those amps and could give me a hand with decision?