Is the AVR-X4800H worth it over the AVR-X3800H?

The X4800H adds more power per channel, a heavier chassis and better components. If you run efficient speakers in a medium room, the X3800H covers most of the same features; the X4800H pays off with harder-to-drive speakers and larger rooms.

Does it support 8K and HDMI 2.1 on every input?

Yes. All HDMI inputs are HDMI 2.1 with 8K passthrough, VRR, Dolby Vision, HDR10+ and HLG, and HDCP 2.3 is supported throughout.

Can I add Dirac Live?

Yes, Dirac Live room correction is available as a paid upgrade. Setup requires a PC and a compatible microphone, and the license is bought separately from the receiver.

How many subwoofers can it run?

Four. Each sub output is independent, so you can set distance, level and bass direction per subwoofer in the menu.

The receiver, a power cord, the Audyssey calibration microphone with stand, a remote control, batteries and an FM antenna. Speaker cables and HDMI cables are not included.

Can it power a second zone?

It has nine amplified channels and can reassign two of them to a second zone. That leaves seven channels for the main room, so plan the layout before wiring.