M-series Mac mini + Denon AVR: eARC hiccups, no-audio-on-wake, OSD snow—anyone solved this?

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Hi all,

Trying to pin down whether I’ve stumbled onto a repeatable macOS/HDMI quirk or just a one-off wiring gremlin.

| Gear | Model / FW |

|-------------------------|----------------------------------------|

| **Mac mini Pro** | macOS Sequoia 15.4.1 |

| **Denon AVR-S960H** | eARC **ON**, HDMI-7 “8 K Enhanced” |

| **Fire TV-Edition set** | 55″ 2023 model – eARC on HDMI 3 |

| Cables | Certified Ultra-High-Speed 48 Gb/s |

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### What I keep seeing

1. **Silent wake:** after the AVR has slept overnight, I power it on → display shows correct input but **no sound** until I reboot the Denon *or* disable eARC.

2. **eARC vs TV-speaker ping-pong:** with the Mac awake, the TV’s audio output flips between *eARC* and *TV Speakers* every time I move the mouse.

3. **Denon OSD snow / black flash** whenever I open the setup menu while the mini is on the 8 K port.

4. All three issues **vanish** if I

*a)* power the Mac **off**, or

*b)* move the Mac to a regular “Standard 4 K” HDMI port, or

*c)* insert a $9 “CEC-less” dongle on the Mac’s HDMI lead.

That makes me suspect the mini is

* hammering the CEC bus with **<Active Source>** every few seconds, **and**

* forcing an FRL ↔ TMDS mode-switch that the Denon’s HDMI board hates.

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### The questions I’d love help with

* **Anybody else seeing “no audio on wake”** when eARC is on **and** an M-series Mac is attached to an AVR’s 8 K/Enhanced port?

* If so, did you fix it without losing 4 K 60 HDR or Atmos?

* Is there a hidden macOS knob to silence the Mac’s CEC chatter?

* Any Denon firmware or HDMI-format tweak that cured the overnight-mute bug for you?

I’m ready to file Feedback to both Apple and Denon, but first I’d like to know if this is reproducible on other rigs (Yamaha, Sony, Marantz, etc.).

Thanks a ton for any breadcrumbs!

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