Like new hon-kwang d12-50 12vdc 500ma ac adapter barrel delivered for $9.00
Input: 120vac 60hz. 15w. wall.
Output: 12vdc .5a. 500ma. tip is +. 3/16" / 5.5mm barrel plug.
Please double check your volt, current and connector requirements.
On a side note, if you do match all three but the form factor (what it looks like) is different, this may still work for you.
Manufactured by hon-kwang model d12-50 self indicates for speakers. Web research: can work with dell a215 speakers. found reference for Linksys AM-12500