Q: iTunes distortion of music during playback - partial solution

Hi.

For a few years,I have been occasionally frustrated by listening to music through headphones on my Macbook Pro with Retna display.  I listen to both classical and rock.  The sound is somewhat distorted and more distorted on more intense parts (loud, dynamic) of the music.  I decided to spend some time on it today; this is what I found.

I picked one song (a classical violin concerto) with to experiment, a ripped several years ago from a CD, now an MPEG4 (192 kbps, 44.1 kHz sample rate) stereo audio file.  While playing I experienced badly distorted intense passages.  iTunes Equalization for that file was None (I assume flat).

I tried multiple headphones of differing impedance.  No difference.  Thinking it might be the analog components in my Mac that were distorting, I tried a USB DAC in combination with differing headphones.  No difference.  The same song, played through my iPad that is only synced (locally - not through iCloud) actually played the music beautifully (no distortion).

So, it isn't analog hardware related.

I used one of my sound processing programs (Amadeus Pro).  I pointed it to open the exact iTunes file from within the iTunes file hierarchy.  I played it and it sounded GREAT.  Totally unexpected.

I went back to iTunes.  After groveling in some old complaints, I found suggestions to run off "Sound Check."   Doing that eliminated most - BUT NOT ALL - of the distortion.  Again, the same file through Amadeus plays and sounds perfectly.

So, either iTunes has problems or there’s something wrong with the program or CODECs.

iTunes VERSION is 12.1.2

I should note that this annoying problem has persisted for years and on multiple laptops through the years.

I have submitted feedback to Apple.

I hope this helps.

  aps