XLS 15 9510 Audio Output configuration settings

I noticed that using a simple Left/Right test audio wav file playback (16bit/44.1kHz), the sound output from the analog headphone output jack has the L and R channels mixed in some way (not perfect separation from L to R channels). Ive tried this with different headphones and both 2 and 3 pole plugs with the same issue. Is there some Audio setting that modifies the output sound other than the Control Panel settings for headphone output?  Using the same test file, the sound output from the onboard laptop speakers IS fine (well separated and not mixed) so this problem is only with the analog output audio from the 3.5mm mic/headphone jack.

Also, for line-in use, this 3.5mm jack is a stereo input correct?