what are the 5.1 speakers you have for? are they for the television (a home theater system)?
if so as stated above, does your control unit have usb input?
remember also that even if it does support usb input, not all file types are supported. what is and what is not supported would be in the manual.
Thanks for the concern...
They are the multimedia speakers with built-in amplifier. Can we plug in an external usb input device that has output of 5.1 channels ? The external usb input device must support playing mp3 files aswell.