Answer:Please refer to the following requirements, configurations and setup procedures.
[Requirements]
OS: Windows 10
Receiver / decoder: Onkyo TX-NR 747 or other receiver supporting HDCP 2.2
Player: Pioneer Ultra HD Blu-ray drive
BD Disk: Most 3D / 4K BD disk movie
Playback Software: Power DVD 14 or later version

[Configuration]
M/B: Z270 Gaming-ITX/ac
BIOS: P2.30

[Setup]
1. When the system boots up, press "F2" to enter UEFI setup screen.
Go to Advanced > CPU Configuration and enable "Software Guard Extensions" in BIOS setting.
Press "F10" to save and exit the BIOS setup screen.

2. Boot into O.S. Install all drivers for the M/B.
Install ME driver ver: 11.6.0.1126 (supports Ultra HD Blu-ray). Download the driver from the following link:
http://www.asrock.com/MB/Intel/Fatal1ty%20Z270%20Gaming-ITXac/index.asp#osW1064
3. Go to Control Panel > Hardware and sound > Sound and select "Receiver output”.