I said above that I feel the difference with the same headphones. After google it, i read that the s3 neo has some kind of audio quality chip made by Wolfson (Featuring class-leading technology, the WM1811 provides crystal-clear voice call quality and enriched audio playback for music and video while minimising power consumption, enabling manufacturers such as Samsung to create outstanding HD Audio user experiences with long battery life.). I don't know what audio chip the a6+ uses, but it's a difference in quality and it's not the phone. I compared 2 other a6+ models with the same pair and same settings and the quality doesn't reach the s3 neo. The a6+ doesn't stand out at some sounds from the background, it makes them sound like a bad quality ogg. I realized that at almost every song, that are some sounds that s3 neo stands them out crystal clear. I don't know what to say more.