An Audio-Video (AV) receiver is the hub of home theater systems, combining audio amplification, video processing, and source switching. Modern models like the *Denon AVR-X3800H* support up to 13.2-channel processing with 8K HDMI 2.1 passthrough. Key features include: Dolby Atmos/DTS:X decoding for 3D audio, Dirac Live or Audyssey room correction (using calibrated microphones to optimize speaker output), and 140W/channel (6Ω) amplification. Wireless standards like WiSA enable low-latency multi-channel audio. Video capabilities include HDR10+/DV passthrough, ALLM (Auto Low Latency Mode) for gaming, and 4:4:4 chroma subsampling. High-end models feature pre-outs for external amplification and Auro-3D support. The latest HDMI 2.1a standard adds QMS (Quick Media Switching) to eliminate blank screens during source changes. AV receivers typically include 6+ HDMI inputs, phono inputs, and streaming via HEOS/Chromecast/AirPlay 2. Models are categorized by channel count (5.1, 7.2.4, etc.) with flagship units like Marantz AV 10 offering fully discrete amplification.