There is no way to downmix the PS4’s audio output to mono. It is recommended to only output chat audio to Cloud Chat and use your TV speakers or sound system for game audio. To do this, please follow these steps below.
  1. Connect the HyperX Cloud Chat to the controller.
  2. From the PS4™ main menu, go to Settings > Devices > Audio Devices.
  3. Set Input Device & Output Device to Headset Connected to Controller.
  4. Set Output to Headphones to Chat Audio.