Everything there is to know about the HDMI IN port on the Fire TV Cube 3

One of the big changes on the 3rd-gen Fire TV Cube, compared to the last two models, is the addition of an HDMI IN port on the back that lets you connect any HDMI device to the new Cube. Amazon hasn’t said much about the new port, other than saying it’s for cable and satellite TV boxes. In reality, you can plug any HDMI device into it. Here is everything about how the port works with the Fire TV Cube and what you can do with a device connected to it.

As mentioned, you can connect any HDMI device to the Fire TV Cube’s HDMI IN port, not just cable boxes. All HDMI devices, whether they be a cable box, game console, Blu-ray player, computer, OTA tuner, or other streaming box/stick, will essentially behave the same way. For the purposes of this article, I’ve connected a Nintendo Switch game console, but just substitute whatever HDMI device you use often and everything I describe will work the same way.

Fire TV Cube input menu displaying live video preview of HDMI IN device.

Of course, once you have an HDMI device connected to the HDMI IN port of the Fire TV Cube, you can switch from the Fire TV interface to that HDMI device at will. This can be done by saying “Alexa, switch to HDMI,” to either the Cube or the remote mic, or you can use the input menu in the Fire TV’s main navigation bar, located between the profile icon and the search icon. When you have the “HDMI” icon highlighted in the input menu, a live feed of the connected HDMI device with audio passing through is displayed in the top right corner. I wish the Fire TV’s interface shadow didn’t cover so much of the lower-left preview video because you could literally just use the HDMI device from this preview without switching to it if you wanted to, as if it were a picture-in-picture display.

The other way to switch to the HDMI IN device is to just wake it up, assuming it supports HDMI-CEC power controls, because the Fire TV Cube does support HDMI-CEC capabilities through the HDMI IN port. So if the connected device is HDMI-CEC compatible, which most modern HDMI devices are, just using the device’s remote will cause the Fire TV Cube to automatically switch to it. Even if the TV is off and the Fire TV Cube is asleep, if you wake the HDMI device connected to the Cube’s HDMI IN port, the Cube will wake up, then wake up the TV, and then switch to the HDMI IN device. This leads to the Fire TV Cube’s next HDMI IN capability, which is controlling the connected HDMI device using the Fire TV Cube’s remote.

If the device connected to the HDMI IN port of the Fire TV Cube can be controlled over HDMI-CEC, then you’ll be able to control it using the Fire TV Cube’s remote. For example, if you have a Google/Android TV streaming device connected to the Cube’s HDMI IN, you can use the Fire TV Cube’s remote navigation ring, select, play/pause, fast-forward, and rewind buttons to control the Google/Android TV device. You can even use voice commands, like “Alexa, Play” or “Alexa, scroll down” to control the connected HDMI IN device, since even those basic voice commands are passed through HDMI-CEC to the connected device. It is quite trippy to be using Alexa to scroll in a Chromecast app, that’s for sure, but it’s very cool that it works so well. For cable/satellite boxes, and possibly other HDMI devices, you can use the channel up/down buttons on the Fire TV remote to channel surf on the set-top box, which explains why Amazon included its Smart TV remote with the Cube instead of the usual Fire TV remote.

Alexa blue voice bar displayed over a Nintendo Switch connected to the HDMI IN of a Fire TV Cube.

So you can seamlessly switch between your Fire TV Cube and your HDMI IN device and you can control the HDMI IN device with the Fire TV Remote, but the capabilities don’t end there. With the HDMI IN device being viewed, you still have full access to Alexa and all of the voice assistant’s usual Fire TV overlays. Issuing a hands-free Alexa command or pressing the mic button on the remote will display Alexa’s blue listening bar on top of the HDMI IN device being viewed. You’ll hear Alexa’s response come out of the built-in speaker in the Fire TV Cube.

Alexa weather forcast displayed over a Nintendo Switch connected to the HDMI IN of a Fire TV Cube.

If you issue an Alexa command that displays a full-screen result, like searching for a restaurant, you can just press the back button when you’re done and you’ll be right back to the HDMI IN device without skipping a beat. Even better is if you issue a command that uses one of the newer compact Alexa displays, like asking for the weather or asking a factual question. Those Alexa interactions pop up right on top of the HDMI IN device without taking you away at all.

Live security camera picture-in-picutre feed displayed over a Nintendo Switch connected to the HDMI IN of a Fire TV Cube.

Zoomed in view of Live security camera picture-in-picutre feed displayed over a Nintendo Switch connected to the HDMI IN of a Fire TV Cube.

While watching the HDMI IN device, you can say “Alexa, preview my [CAMERA NAME]” and a picture-in-picture feed of your camera will be displayed over the HDMI IN device. From there, you can press and hold the home button on the Fire TV remote to enlarge or dismiss the camera feed, or you can use voice commands to do the same. The Fire TV Cube is capable of automatically displaying the PIP video feed of compatible smart video doorbells when someone is at your door. I assume that the PIP popup would also be automatically displayed over the HDMI IN video as well, but I don’t have a compatible doorbell to test it myself.

Many Fire TV overlays displayed on top of the HDMI IN video on a Fire TV Cube.

Basically, anything that can be overlayed on top of the Fire TV interface can also be overlayed on top of the HDMI IN device. Above is everything I could think to activate simultaneously, being displayed over a Nintendo Switch connected to the Fire TV Cube’s HDMI IN port. You’d obviously never actually display all of that at once, but it demonstrates the Fire TV Cube’s ability to overlay information and features on the HDMIN IN device.

PlayStation 5 Video Output Information screen while connected to the HDMI IN of the Fire TV Cube.

As for the technical capabilities of the HDMI IN port, it’s limited to the same 4K @ 60Hz video that the Fire TV Cube is limited to. So if you connect something like an Xbox Series X or PS5, you will not be able to pass 120Hz video through the Fire TV Cube or be able to use VRR. (Huge thanks to AFTVnews reader Beau Taylor for testing that for me!) However, the HDMI IN port of the Fire TV Cube can pass Dolby Vision and HDR10 video just fine. I assume HDR10+ video will also pass through fine, but I couldn’t test that.

By default, the Fire TV Cube will upscale or downscale all video coming into the HDMI IN port to match the output resolution that your Fire TV Cube is set to. So, for example, if the Cube is connected to a 4K TV and set to output in 4K and you connected a Nintendo Switch (which is only capable of 1080p) to the HDMI IN port of the Cube, the Cube will upscale the Switch to 4K and the TV will indicate that the Switch video is in 4K. As far as I can tell, the Fire TV Cube is not using its new “Super Resolution” upscaling feature to do this, since turning the feature on or off seems to make no difference to the upscaled HDMI IN video. The benefit of allowing the Fire TV Cube to upscale/downscale HDMI IN video, as needed, is that your TV then doesn’t need to switch between resolutions each time you switch between the Fire TV interface and an HDMI IN device with a different output resolution. Resolution switching, especially on older or cheaper TVs, often results in a jarring black screen being flashed each time, so letting the Cube upscale/downscale video will void that.

HDMI In Passthrough Setting on the Fire TV Cube

If you prefer that the Fire TV Cube does not upscale/downscale any HDMI IN video, you can switch an option called “HDMI Input Passthrough” from OFF to ON in the Fire TV Cube display settings. Turning this option on will force the Fire TV Cube to match the resolution of the HDMI IN device when switching to it and then switch back to the Fire TV Cube’s own resolution setting when you switch back to using the Fire TV interface. With the Cube set to 4K, I did find that the Nintendo Switch’s 1080p video was slightly crisper when the Fire TV Cube was not set to upscale its HDMI IN video, but this came at the expense of screen flashes every time I went in and out of the HDMI IN video. For me, the image quality difference wasn’t noticeable enough to not let the Cube upscale the video feed, but better TVs with better built-in upscaling may result in a more noticeable difference.

The 3rd-gen Fire TV Cube does a great job of making its HDMI IN port much more than just a 1-port HDMI switch. Essentially, it allows you to treat a separate HDMI device as if it were just another app running on your Fire TV. It’s very seamless to jump between the Fire TV interface and the HDMI IN device, much more so than asking Alexa to switch TV inputs or using your TV’s remote to switch inputs. This is made even easier with the “Recent” button on the Fire TV Cube’s remote since “HDMI” appears in the recent app list as well. If your HDMI device supports HDMI-CEC control, the experience is even better because you can use the Fire TV Cube’s remote to control the HDMI device and even use basic Alexa voice commands to control it. All of that and you also get to retain the convenience of on-screen Alexa capabilities while using the HDMI IN device. It all works so well that it makes me wish there were more than one HDMI IN port on the Fire TV Cube.

See all my 3rd-gen Fire TV Cube coverage here.

35 comments
  1. Cube Newbie says:

    I have realized as a first time oled and cube buyer all of this information can be overwhelming. Elias, can you please post an article on essential 4k tv settings for the cube for first time buyer-user. Thank you!

  2. Tim Sullivan says:

    I’m interested in how much video lag there is with gaming consoles on the hdmi in.

    • Great question. My crude test shows about 60 milliseconds of lag added when going through the Cube’s HDMI in port. I used my phone’s 240 fps slow motion camera to record button presses both directly to the TV and through the HDMI IN. The difference was about 15 frames slower for the HDMI IN port. So 15/240 = 0.625 seconds or 62.5 milliseconds.

  3. Craig says:

    It took a few hours of tweaking everything, but I got my DTV Stream Android TV box ran through the Cube 3 and Harmony configured for it. Getting things to run from the DTV Stream box to the Fire TV Cube and then to my Philips Hue Sync box to my Sony A/V Receiver and then Sony Bravia and then the button sequence for the Harmony Activities needed to make it seamless exiting/handoff switching, was a bit of effort, but I managed it. #roku_soundbar_codes #airplay2 #matter #matter_cast

  4. Rik Emmett says:

    This seems similar to the logitech review device from many years ago. One could integrate a Tivo DVR with the FireTV cube and possibly control both with a single remote.

  5. Zip says:

    Having my Xbox Series X in the HDMI input and switching the Speaker audio to Headset Format. It will push Dolby Atmos spatial surround sound to a capable Alexa Home Theater Group

  6. Sam says:

    I have a MIbox Android connected to my cube’s HDMI, but I can’t get the cube’s remote to control it. I have to use the separate MIbox remote, the cube’s remote does not do anything.
    Is there some setting I can change?

  7. D Bangin says:

    I’m curious if this Fire Cube has the same bug as the 4K Max and the 4-Series TV (and also until Sep 2022 the Omni-Series TV) that prevents it being added to a group in the Alexa app?

  8. Gaamer says:

    Is there any way you could test if this supports Auto Low Latency Mode for games through a supported TV? Not sure if you have atv with that feature

    • Yes, the Cube does support ALLM. There is an option the Cube’s display settings where you can set ALLM to Auto/On/Off. The setting says it’s for both gaming on the Cube and for “connected gaming consoles” so I assume that means the HDMI IN supports ALLM as well, but I don’t have a way to confirm that myself.

  9. Emu says:

    Does the HDMI in port support ARC? I’d like to connect my receiver to the in port to be able to have multiple HDMI sources pass through but still be able to use my receiver’s speakers for FireTV content.

    • Thanks for bringing this up. I didn’t think to test ARC. THe Cube is at my desk right now but when I get a chance to move it to my main TV where I have ARC devices, I’ll be sure to test that and update this comment and the article.

  10. FRANK ENGELMAN says:

    Does it support Airplay and HomeKit like the Omni Fire TVs?

  11. Kris says:

    Hi. I am having a problem: audio from satellite box connected to HDMI IN of Cube does not come through to my soundbar… everything else like youtube, netflix on cube works fine just no audio from SAt box? What am I doing wrong (don’t think there should be a spetial output setup on sat box for it- should be straight forward). Thanks

  12. Branden Steinberg says:

    Some interest behavior I have noticed after setting this up with my Verizon FiOS box:
    – Video is up scaled to Dolby Vision. My cube is set to “adaptive.” Cable box resolution set to 4k. This is happening on all content.
    – Channel up/down does not appear to work on the remote, but it works fine via Alexa
    – Functionality seems missing. For example, there is no way to trigger the cable box menu (that I am aware of).

    I am going to test this out a bit, but I may revert back to plugging into another HDMI input on my TV, as I’m not seeing the benefit here. I could already control the cable box with Alexa.

    My TV is a Sony A8G

  13. Tired_ says:

    Does the Alexa Home Theater function that the Fire Stick 4K Max has, where you can send the audio to one or more Echo devices including other devices on your TV through HDMI-ARC, work on the new Cube? If so, does it send audio from the HDMI-IN device to the Alexa Home Theater?

  14. chris says:

    Hi, you say that the N.Switch has no image enhancement (super resolution) when plugged into the HDMI1 port. Have you tested with a video playback device to see if it works with videos?

    Overall what do you think of this Super Resolution function? Compared to the upscal of the Shield TV?

  15. Larry Hill says:

    I plugged my comcast x1 cable box into the cube input but it did not control the box via voice commands. I could change from fire tv to cable via the remote only. Amazon customer service told me to not use the cube input and that gave me some control, but if I said change to cbs, it would switch from cable to fire tv input. Saying channel up or down didn’t work.

  16. Adel abumari says:

    Hello Elias
    I don’t seem to find information about how to put the system in picture in picture using the apps of the cube or the apps of the cube in combination with the input video

    • The HDMI IN device cannot go into the picture-in-picture window and Fire TV apps that support picture-in-picture cannot go on top of the HDMI IN device. So the only PiP possible regarding the HDMI IN is security cameras.

  17. Joshua Sands says:

    I am having an issue with the HDMI input on my new Fire TV Cube. My Meta Portal TV will not show up – “No Signal Detected”. My iPhone plugged in via HDMI using an adapter works fine. Just seems to be an issue with the Portal TV. Strange thing is, when I then unplug the portal TV from the Fire TV Cube and then plug back straight into my Toshiba TV, it has a very weird squashed picture. When i restart the Portal TV, the picture is then fine again when plugged directly into my Toshiba TV set. Is this anything to do the Refresh rates on the Portal TV? Or CEC issue?

  18. Steve Meyer says:

    I’m having AV Sync problems with Gen3 that I didn’t have on Gen2. AV Sync seems to be off depending on the streaming service being watched. I’ve adjusted the AV Sync control many of times only to get it right on HBOMax then it is off on Disney+ or Netflix. The Gen2 had a 20ms delay which when compensated for was right on for all streams. Hopefully there is something in a future software update that will fix this issue.

  19. Bryan Tobing says:

    The only reason I’m interested in the new Fire Cube is the HDMI-in functionality so I can use my Echo Studio without lag as there is noticeable delay even when using the AUX input. Do you think this would work? I love the Echo Studio and want to use it for movies and gaming but any external source outside of the Fire TV and there is noticeable delay.

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