I have had the same problem with my 2015 spark with man. trans. In total it has probably stalled out 40 times. Never has tripped a trouble code. It will also stall out while at idle or when stopped in neutral. I have just under 7900 miles on my car and bought it last March. This car has been in the shop 6 times and they can't find anything wrong, one time the service manager kept the car for three days and racked up 300 miles on the car with the computer hooked up with no problems found. I think they think i'm crazy but the car has a problem. You need to take your car to a dealer and complain.
Changed the settings on my radio today, what a big difference. Just might leave the stock speakers in the car for awhile. Thanks for the info on this topic.