Windows 7 Service Pack 1 is being released to the general public this week via Windows Update (possibly starting tomorrow).
According to the release notes one of the fixes is;
"Improved HDMI audio device performance - A small percentage of users have reported issues in which the connection between computers running Windows 7 and HDMI audio devices can be lost after system reboots. Updates have been incorporated into SP1 to ensure that connections between Windows 7 computers and HDMI audio devices are consistently maintained."
If anyone observes improvements with their setups after installing SP1, including HDMI connection after powering equipment on/off in different sequences, after resuming from sleep, etc. please post and let us know.
Samsung UN65JS8500 65" SUHD TV FW1455; Yamaha RX-A750BL Receiver FW1.77; Samsung UHD-K8500 UHD BD player, FW1005, w/dual HDMI; one to TV (video), one to AVR (bitstream); Arris DCX-3600M Cable STB; Nvidia Shield Android TV Update 3.2, Server: Windows 10 Home and Emby Server.