If I follow correctly, what you need is some audio mixing type device that can output a microphone to a set of speakers and amplify it to speakers in the room. This will really switch you away from USB connected devices into professional AV equipment, there are lots of options. 


Something like a Behringer XENYX Q802USB would handle the audio, then some wireless mics and amplified speakers.


You won't achieve reliable in room amplification via USB devices.