We've had a few emails about this!
Here are the settings for HD-Audio passthrough in Kodi on H8:
7.1 and 5.1 Channel HD-Audio via HDMI
In Android settings:
Settings - Playback - Output: HDMI.
In Kodi settings:
SYSTEM - Settings - System - Settings level: Advanced.
SYSTEM - Settings - System - Audio output: Number of channels 7.1.
SYSTEM - Settings - System - Audio output: Enable passthrough.
SYSTEM - Settings - System - Audio output: Dolby Digital (AC3) capable receiver
SYSTEM - Settings - System - Audio output: DTS capable receiver
SYSTEM - Settings - System - Audio output: True-HD capable receiver
SYSTEM - Settings - System - Audio output: DTS-HD capable receiver
5.1 Channel HD-Audio Only via HDMI
In Android settings:
Settings - Playback - Output: HDMI.
In Kodi settings:
SYSTEM - Settings - System - Settings level: Advanced.
SYSTEM - Settings - System - Audio output: Number of channels 5.1.
SYSTEM - Settings - System - Audio output: Enable passthrough.
SYSTEM - Settings - System - Audio output: Dolby Digital (AC3) capable receiver
SYSTEM - Settings - System - Audio output: DTS capable receiver
5.1 Channel HD-Audio Only via S/PDIF
In Android settings:
Settings - Playback - Output: SPDIF.
In Kodi settings:
SYSTEM - Settings - System - Settings level: Advanced.
SYSTEM - Settings - System - Audio output: Number of channels 5.1.
SYSTEM - Settings - System - Audio output: Enable passthrough.
SYSTEM - Settings - System - Audio output: Dolby Digital (AC3) capable receiver
SYSTEM - Settings - System - Audio output: DTS capable receiver