Now that Ultra HD TVs are poised to hit the market in force, it's more important than ever to have receivers that can handle them -- even if our bank accounts often can't. Harman Kardon knows this well enough to ship its AVR 2700 and AVR 3700 receivers, both of which carry 4K passthrough and upscaling on their eight HDMI ports as a matter of course. The two also support AirPlay streaming alongside more commonplace DLNA media sharing and offer remote control mobile apps. Home theater futureproofers mostly have to decide on audio channels and network support before they buy: the $800 AVR 2700 produces 7.1-channel surround and sticks to Ethernet alone for networking, while the $996 AVR 3700 introduces 7.2-channel audio and WiFi. Few of us will use either receiver to its full potential right now, but well-heeled 4K TV owners (or just the well-prepared) can pick one up today.