I am also curious about this and have a recommendation that seems ingenious. Both systems have their own power source, so what if you power both on and use a 3.5mm jack splitter (I’ll attach a photo) to connect your device to both systems? If they’re the same exact system and powered by their own source, only connected via aux jack, I feel like this would work with the exception of maybe one system sounding a little different due to age or whatever may cause quality to diminish. I’m very curious to see if this works, as I have acquired a free pro media 2.1 system and am considering buying another with how cheap they are. Love this system and think this could be a great way to get more sound.