I'm presently running Emby on Debian Linux "Buster" & Open Media Vault, powered by a circa 2011 AMD Phenom II X4, no GPU. The hardware has had a great 10-year run and is ready for retirement.
Upgrade plan:
CPU: Intel Quick Sync, likely Core i5-11600K 11th Gen Rocket Lake 6-Core 3.9 GHz UHD Graphics 750.
Motherboard (may not matter much for Emby): quality build, multiple M.2 slots, plenty of SATA connections, 1gb/2.5gb ethernet.
Working storage: fast M.2 SSD for