The Good: The Amazon Fire TV Cube lets you control power, input switching and volume on your TV, sound bar or AV receiver hands-free from across the room, using only voice commands. You can also use your voice to change channels on a cable box. The microphones are superb at recognizing voice commands from afar, over the blare of speakers. Device control setup is as simple as possible. The Bad: If you want to use a source device beyond Fire TV -- like your cable DVR, game console, smart TV, Roku or Apple TV -- you'll have to keep its remote on-hand. The included Fire TV remote can't control other devices and even lacks volume and mute keys. Many apps don't support voice yet. The Bottom Line: The Amazon Fire TV Cube's well-designed voice controls make it a superb alternative to a standard universal remote, especially for simpler systems. If you have a TV entertainment system with a bunch of devices, a universal remote like the venerable Harmony is the still best way to make it easy to use. But the new girl in town, Alexa, is now a close second, thanks to the Fire TV Cube.With the Cube installed, saying "Alexa, turn on the TV" from across the room will power up your television, and AV receiver or sound bar if you have one. Whatever you were watching last -- say, TV from your cable box -- appears on the screen, and audio comes through the speakers. "Alexa, switch to Xbox" switches inputs so you're ready to pick up the controller and mow down some enemies. "Alexa, watch Stranger Things on Netflix" switches inputs again and starts streaming the Upside Down immediately via Fire TV (in 4K and HDR, if your gear supports it). "Alexa, tune to CBS" switches again to your cable box, changes the channel and boom -- hello, Judge Judy. "Alexa, play Talking Heads" fires up the Spotify app and Psycho Killer plays through the speakers on your TV, receiver or sound bar -- bypassing that cruddy Alexa speaker -- and the Talking Heads playlist appears on-screen. "Alexa, next" plays the next song, This Must Be the Place. "Alexa, volume up" cranks those speakers even higher. Finished? "Alexa, turn off the TV" powers everything down.If you're used to pressing buttons on a remote, or God forbid, more than one remote, using Alexa on the Cube can make you feel like Gandalf himself.You can do all of that stuff by pressing buttons on a Harmony remote too, and in many cases, like browsing for shows, fast-forward and pause, buttons are easier than using voice. And for Harmony owners (like me) who use Harmony's existing Alexa voice skill with their Echo speakers, adding a Fire TV Cube to the arrangement probably isn't worth it. The Cube isn't a full-on Harmony replacement. Its included Fire TV remote doesn't control volume or mute, a big misstep on Amazon's part that I hope it fixes in the next generation. You'll still need to keep your cable box remote if you want to do more than just switch channels -- the Cube can't control the box's DVR (yet). It also can't command Blu-ray players, Apple TV, Roku or other non-Fire streamers, so plan on keeping those remotes handy, too. And like any Alexa veteran knows, you can't expect it to recognize and execute your commands correctly the first time, every time. None of those issues can spoil the feeling of wonder that comes with getting your dumb, frustrating entertainment system to obey spoken commands. I got a dose of it when Amazon launched Fire TV control via Echo speakers last year, but that system couldn't tame your audio equipment or switch inputs. The Fire TV Cube is one of those special devices that breathes new life into your existing tech gear, making it more fun and easy to use than ever. Get to know the CubeThe $120 Fire TV Cube is designed to sit near your entertainment center because it plugs into your TV, receiver or sound bar via HDMI.It has all the capabilities of the $70 Fire TV streamer, including 4K HDR video and Dolby Atmos sound. It lacks HDR10+.It also has all the capabilities of the $50 Echo Dot speaker, including a built-in speaker and a mic array to pick up your voice commands. It's always listening for the "Alexa" wake word.Audio from music, TV shows and movies are piped through your TV, sound bar or AV receiver speakers by default, significantly improving audio quality. Often Alexa's voice is, too, but sometimes she comes through Cube's built-in speaker.Includes a Fire TV remote, which also accepts voice commands when you press the mic button and speak into it (you don't have to say "Alexa").Built-in infrared emitters inside the Cube blast the room with infrared signals to control your gear.Includes a separate corded IR emitter with an 8-foot cord to reach gear behind cabinet doors, and an Ethernet adapter in case you don't want to use Wi-Fi.The sides are glossy black plastic and a bright Alexa LED response strip is along the top front face. Top keys control volume, mute, and activate, just like a late-model Echo speaker.It's small -- somewhere between a Dot and a full-size Echo -- but not a perfect cube, measuring 3.9 inches wide and deep by 3 inches tall.It's only available in the US for now, but the $120 price converts to about \u00a390 or AU$160.Alexa heard me over the musicOne of the first things I wanted to test on Fire TV Cube was its ability to "hear" me from across the room with the music blasting. Since it's designed to sit near your TV, the Cube is probably closer to your (potentially very loud) speakers than it is to your mouth. In my test setup sitting around 10 feet away, it worked beautifully.With a speaker less than 2 feet away from the Cube and blasting music, I kept saying "Alexa, volume up" and it kept working. I had to raise my voice slightly when it got really loud, but I found myself doing so naturally, just to compensate for the music. I only had to shout "Alexa" when it got ridiculously loud.Once the Cube recognized "Alexa" it lit up and paused the music (or TV show or whatever) so it could better hear the rest of my command, just like an Echo. If it wasn't able to pause, for example when I was watching a show on my cable box, it instead sent a mute command to my sound bar or receiver's speakers. In both cases it was worth waiting a second or two for silence before issuing the command, something that took me awhile to get used to.Either way, the Cube was a superb listener in my test setups. Your mileage may vary depending on how you position it relative to your speakers. If you have issues, try to put as much distance as possible between the Cube and your speakers, and avoid aiming them at the little box if you can help it. I didn't test the Cube with other Alexa speakers in the house, but when I asked Amazon's representatives what multi-Alexa households could do to avoid confusion, they recommended placing non-Cube speakers in other rooms, as far as possible from the Cube. You could also change the wake word, for example calling one of the other speakers (or the Cube) "Echo" or "Computer."Device control via voice, CubedSure the Cube can do all that Fire TV and Echo speaker stuff -- stream Netflix, Hulu and YouTube, give a weather report and control your lights and thermostats, all via voice or using the Fire TV remote -- but its real differentiator compared to existing Alexa products is device control. Amazon reps told me it can command "tens of thousands" of devices, roughly 90 percent of devices in the US, but didn't cite a specific number. For the record, it worked successfully with every device I tried, including:TVs: Samsung UN55H6350, Vizio P65-E1, LG OLED65C8PReceivers: Denon 3808CI, Marantz NR1508, Sony STR-DN1080Sound bars: Sonos PlayBar, Yamaha YAS-107, Vizio SB3621Cable box: Motorola QIP 7232 (Verizon Fios)The Cube's setup menus list myriad other devices and brands -- the TV brand list alone went from Accele to Zyowaiyu (nope, I've never heard of them, either) and took me 21 seconds to scroll through at breakneck speed. I have no reason to doubt Amazon's 90 percent claim. If your brand somehow isn't listed, however, the Cube won't be of much use to you until Amazon adds support -- there's no "learning" function as seen on many universal remotes.Using infrared commands, or occasionally HDMI CEC, the Cube successfully turned my devices on and off, changed inputs, adjusted volume and, in the case of the Fios box, switched channels. More advanced commands, for example changing surround modes on a receiver, picture modes on a TV, aren't supported (yet). I was also unable to perform any DVR functions on the Fios box, including pausing live TV, browsing the program guide, or scheduling or playing back a recording.