I have been using the PreSonus Audio Box USB 96 for a few years now and it works pretty well.
One issue though when we are broadcasting our live sporting events is the fact that we are using two headsets (Sennheiser) and the connector from the XLR connect don't reach to the back left and right main out ports. So I ran a Y cable out of one of the ports back to each of our individual headsets which gets the job done/

Is there a better way to do this instead of having to purchase a mixer?

One other note is when you listen back to the broadcast me and my partner are on different channels and it sounds weird especially on a moble device. But with all of this being said the audio quality is top notch, but I still want it overall to be better.

Thanks for the help