Am i right in thinking that all usb speakers have their own sound card on board? I have a pair of logitech z120 I want to try out with this (and then maybe hook

Am i right in thinking that all usb speakers have their own sound card on board? I have a pair of logitech z120 I want to try out with this (and then maybe hook it all up to a battery to make it completely wireless) but i've left them at uni and can't try it out yet.