I never required stereo, mainly because your audiences cannot hear it for the most part, and I primarily played to audiences ranging from as few as a dozen ppl, to more than 1,000 ppl. Keep in mind that even with a live band, the audience gets mono - not stereo.
Now, if you, personally, wish to hear stereo, just use the onboard speakers, or high quality headphones.
When I was performing to larger audiences, I frequently used a pair of Bose L1 Compacts, and prior to that a pair or Barbetta Sona 32SC PA speakers. When I switched to the Bose L1 PAS system, which was the forerunner of the Bose L1 Compact, I no longer had stereo, however, I had a great 10-inch, 250-watt sub, plus 24 speakers on a 7-foot column. I had virtually no fall-off at 100 feet, far cleaner, crisper sounds, and everyone in the audience could hear the same volume and quality, regardless of where they were positioned in the venue, something that you cannot do with conventional sound systems.
Your best bet would be to add a second Bose L1 Compact to the setup. Your audiences will love what they hear.
Good Luck,
Gary