I have a Sonos ARC and I get 5.1 surround sound with my HDHomeRun and Apple TV 4K.
I even posted a photo of it earlier showing that I'm getting 5.1 in the Sonos app.
Your understanding and assertion that the HDHomeRun cannot supply 5.1 audio is incorrect.
Apple TV does not output DD 5.1 unless you set it to and then you lose the ability for Atmos. Normal audio out of the Apple TV4k is 5.1 uncompressed.
Also, not all channels are 5.1. If this is OTA, the 6 channel audio is on ABC, NBC, CBS, Fox, CW, and MyTV. Most PBS, ION, and the sub-channels for any main station broadcast 2 audio channels.
@tmm1 This is sort of off topic, but since you have an Arc and you might know a thing or two about Channels I figured I would run this by you. 
I recently got a Sonos Arc, which I am using with a 2021 ATV 4K. Sometimes with Channels content, the audio is significantly ahead of the video. Do you experience that as well? I know there are a ton of factors at play here, and I am not suggesting that it is a Channels issue. And I know Sonos has an adjustment for this but it is sort of a pain to use. Just wondering if you have experienced this as well, and if you have any suggestions. Thanks in advance!
I have not experienced any sync issues.
Usually if you're feeding through the TV (via HDMI ARC), that's the source of any delay.
Thanks for getting back to me so quickly. Yes, I have an HDMI going to my LG TV and then back out to the Sonos Arc. I don't think there's really another way to do it, right? Aside from an HDFury Arcana, which is stupid expensive.
Im' doing the same with my LG. You can look in the TV's settings and switch the format to prevent postprocessing on the TV
I thought I had all post-processing turned off, but I will go back and check again. You are referring to both audio and video post-processing, right?
Do TVE channels not output surround sound? I can’t get sound out of the center channel speaker on those type of channels but local OTA through 4k home run do? Instead of TVE sound comes out the tv speaker instead
TVE channels are stereo only, no surround.
Figures but shouldn’t I still get the audio out of a center speaker instead of the tv?
When a channel is in stereo (2.0), you only get sound out of the left and right front speakers. Nothing from the center speaker.
Are you saying when using hdhr content sound is coming out of an avr to stand alone speakers but when you switch to tve content sound comes out of the tv? This sounds wickedly weird. If this is the case can you explain all devices and how they are connected and in what order. If the tv is outputting sound to say a sound bar with satellites over optical cable you may need to check settings within the tv and enable stereo along with multi channel output through optical. Please explain your setup
Actually most modern avr’s would automatically initiate pliiz and simulate surround sound using all speakers. Unless “direct” or equivalent setting is chosen
I'm saying I have a Denon X4400h receiver. I have this HD Homerun connected to bring in local OTA channels including ATSC 3.0 that will be available in my area it appears soon: HDHomeRun FLEX 4K - SiliconDust
I also have an Apple TV 4k and Nvidia Shield 4K hooked up to the receiver. I am using the ARC feature on the TV to send all sound through the receiver.
What I am saying is that when I watch local OTA programming that is being picked up by the HD Homerun on Channels that yes I am getting sound out of the center channel speaker (not a soundbar. I am using a Monoprice Monolith 365C THX speaker). However, it appears all TVE channels all sound is coming out of the television speaker (instead of the center speaker above) and the two left and right front speakers). And obviously I don't want it using the television speaker but the actual center channel speaker...
Sorry, but this doesn't make sense. You're either sending all sound via the client devices into the receiver, or sending them to the receiver via the TV with the clients hooked up there. ARC wouldn't come into play if the ATV and shield are hooked into the receiver.
TVE is stereo only( left and right speakers) Set your receiver to DTS Neural X to emulate surround. You must have a setting on your Tv to allow the center speaker on your tv to work with your receiver. Turn it off
So there must be a setting that needs changed in the tv. If you can’t find a setting try disabling tv speakers or even better just attach atv and shield hdmi to the denon first. Then denon to tv and disable speakers in tv and done
The HDMI was not in the arc port on the tv. I fixed it and then choose “movie” button on the receiver remote and it lets me select Dolby Surround and get dialogue come out of the Monolith 365 C speaker instead of the built in tv speaker
It would be cool if you guys could have a setting to pimp the TVE 2 channel audio to simulated 5.1. I realize this is a lot of work and not just a setting.
The SiliconDust implementation (while fare from perfect) is huge improvement from 2 channel audio to 5.1 (on ATSC 3.0 content) on the AppleTV.