Ear fatigue in 2012 XC70?

[alexXC70]

Evening all.

Drove home our new 2012 XC70 (Premier, Climate), which has the standard "high performance audio" that comes with the base model.

Can't listen to more than 5 minutes of music before ears start to tire. Happens whether listening to CDs (where the music is in WAV format) or via Bluetooth to the iPhone (with Apple's AAC encoding) or via USB with an iPod (combination of MP3, WAV, AACs).

I've played with the EQ as well as the standard Bass and Treble settings. I've turned off the Velocity adjustment. Nothing helps.

The only thing that SEEMS to lessen the effect is to listen only to the front speakers (with the fader tilted 100% forward).

I wonder if perhaps one or more speakers is out of phase, wired incorrectly somehow.

Any one else heard of this? Any suggestions?

Many thanks!