While I personally have not used one. Google 3.5mm 2 in 1 out mixer
here is one I found on amazon that should get the job done. Look around for one you like in your price range.
Edit: looks like the reviews say that one sucks but just use it as an example for what you need.
Oh, I wasn't aware of that. Not a huge audio techie myself. Would this be an alternative then? Do you know of any other solutions to get simultaneous play out of the speakers?
That's just free-market capitalism. Companies try to disrupt each others sales all the time. Look at Lyft and Uber- constantly trying to take out the competition.
Also, Behringer's Swing has it's own firmware and added functionality, so it's not a 1:1 clone.
How about all of these 4 channel mixers? Are they all trying to disrupt Behringer's sales?
Why don't people get upset about this?
I think I'd prefer simultaneously. In that case, would something like this do the job, along with some 3.5 mm to 1/4 inch adapters?
EDIT: If you could point out any other mixers then that would be great. Just looking for the best deal while still maintaining decent quality.
Honestly, it's 30 bucks and they know many people will buy it. These people make a KILLING off of accessories, and they know not as many people will buy it at 30 bucks if it doesn't have the headphones. So they throw in a cheap 1 dollar pair of headphones to make it "seem worth it". I'm probably going to just buckle down and buy a cheap 4 channel mixer and use that instead, I'll only ever be playing with voice chat at home and I need the mixer anyway. Something like this will do the trick just fine and give you 2 extra channels for, e.g. piping in external music.