Audioengine USB Power Adapter
Crutchfield Customer Review (What's this?)
Product works as advertised - what's not to work. A bit pricey (yes, no one made me buy it). Not sure if I missed it in the product specs (adviser informed me) that when using the Audioengine D1 DAC with fiber input, external power is required. Have not tried using the product with any device other than the D1.