clip+ and portapro

just got my sansa clip+ (firmware 01.02.15).  plugged in my portapro and set volume to max or near max level. music play becomes choppy.  when i lower volume to halfway, it plays perfectly.  

tried using the stock earphones and it doesn’t have the same issue.  does anyone have an explanation for this?  is there a fix for it?  thanks to advice.

up

The Portapro is not a good choice for use with the Clip+. If you are using the equilizer, you could try setting the equilizer to neutral. That might help. You could try using a more efficient headphone or earphone, perhaps one that is 16 or 32 ohms.

it seems like the headphone amp in the Clip+ is clipping.