Reply to Routing Audio, 2 computer,2 soundcards,2 Maschines (For Jamming)

Hello Forum members

So, my bro is coming back from college and I want to know if theres anyway he can use his maschine mikro connected his computer, while i use my computer and maschine. BOTH COMPUTERS RUNNING ON THE SAME PA SYSTEM.. i have 2 soundcards available one with no in ports but another one with 2 inputs.

How would the routing work to get both computers blaring beats over the speakers?
-would it work to connect each soundcard in a computer,then with the outputs of one connect it to the "inputs" of the other, and from there conect to the PA System??

please help!

I just want to know cause i want to jam out with some drum tracks. and maybe this could facilitate production as welll

hopefully you were able to understand my message...THANK YOU!