[prototypedc]

it is the adapter but its not defective and it is stereo. im not sure how to explain it but it has some thing to do wit how the contacts are lined up in the adapter,

you can tell what i mean if you use a stereo headset that was made for a cell phone with a 2.5mm plug with the contact for a mic you will hear stereo sound,

but if you use (most if not all) 2.5mm to 3.5mm adapter with out a mic contact you will only receive mono sound,
{do to the lining up of the contacts in the adapter}