How to make MX122 ARC HDMI work?
 

My new TV streams Amazon Prime and the new TV has an ARC setting to pass audio via HDMI back to the receiver, or preamp in this case.

While my TV certainly has a setting and a dedicated HDMI2 (ARC) input, and my MX122 has a HDMI Monitor (ARC) output, I don't see any settings in the MX122 setup.

Anyone have some advice?

I'll be following this thread closely as I'm on the fence about purchasing a mx122 myself to integrate into a existing 2 channel system. What brand and model tv are you using.

LG OLED 77", I don't remember the precise model number though. LG is pretty intuitive as I've never heard of ARC until playing around in the settings.

Happy to share the settings I use. I have the MX121 ARC out via HDMI into TV input (I believe it’s video) and an HDMI out from the cable box into the MX121 3(SAT) (I believe that is audio). See if that works for getting A/V when your MX122 front input dial is tuned to SAT. Hope I did not lead you astray.

For those that don't know, ARC (audio return channel) is a setting that allows you to use your TV's sound as the source. It's especially helpful if you like Netflix and Amazon Prime, allowing to use your TV as the streaming device and still hear audio from your McIntosh system.
You need an ARC capable TV and ARC capable AVR or Preamp like the MX122. You'll also need an HDMI 2 cable with ethernet and arc capabilities. There are settings in the TV that allow you to enable ARC and bypass the TV's internal speakers.

Below is the setting that took several emails to make the magic happen. I no longer need a separate device like Amazon Fire TV.
Attachment 52725

This is especially helpful because Mc doesn't offer Netflix and Amazon streaming, and the newer OPPO 4K players don't either.

Good data.

Can I hitch on and ask if this works on the MX121? The ARC HDMI connection on the MX121 is labeled as an ‘out’.

It should if monitor out has an ARC option.
You always have the TV as an OUT, arc is just the return. There may be some settings to play around with in both the MX121 and your TV, and the TV also needs to have ARC. TV audio is also a source option on the MX122. Instead of CBL and DVD you need to set to TV audio.

I have the MX121 ARC HDMI out going to my TV connected to its HDMI ARC input. Perhaps I need to connect my MX121 to another HDMI input on the TV and the TV ARC HDMI to another input (sat Cable) on my MX121? Then when I watch Netflix us ng the TV app, I will set the MX121 to that other input eg Cable?

This is all the wiring you need to do. Make sure it's an HDMI 2 cable, look up it's specs online that it's capable of ARC.
Go into your TV's settings and tell it to use ARC which disables the TV speakers.
Go into Mc settings and look at the picture I posted above.