Context matters here. A dedicated power amp is superior if you're talking about music quality. However, AV receivers are much more than just amplifiers. They're the hub of a home theater or gaming setup (or one that does both) and offer a vast range of wired and wireless connections. Incoming audio gets routed to their amplifiers and into whatever speaker system you use. AVRs can also pass the video content from streaming boxes, cable boxes, Blu-ray players, and game consoles to your television. They don't process the video; they pass it through in whatever format it's in, assuming it's one they support.