It seems the audiomxd process is consuming 100% CPU on your iMacs, likely due to driver issues or conflicts with the Core Audio framework, especially after the macOS 15.2 update. This could involve audio hardware or third-party software like Audacity and Adobe Audition. Consider rolling back to a stable macOS version, resetting the PRAM/SMC, and testing without audio software installed to isolate the cause. Analyzing system logs might help pinpoint the issue, and since you’ve already filed a bug with Apple, staying updated on any patches or fixes is advisable.
One of my machine's is experiencing this issue - very obviously :(
Near 100% CPU age by 'audiomxd' but only while the machine is (supposedly) sleeping. Utilisation drops to essentially zero once the user is active again, then case temperature plummets from ridiculous to minimal.
The user account has already been abolished then rebuilt with an alternate home folder name but the issue returned days later.
MacMini M4Pro Sequoia 15.2 with several AirPlay speaker options available, a Studio display for regular audio and a Jabra headset (via TB4 KVM).
Grabbed while logged in: this duration was accumulated overnight, leaving the machine hot to the touch in the morning.
Sorry, no solutions, just the same hair-pulling frustration...
Ahh, I also have BlueUtil installed (for shortcut removal of the BT keyboard rather than for audio purposes) but not familiar enough to determine these details.
A thought: what about WiFi? I believe AirPlay uses both?
I noted this evening that the M4 iMac is suffering too, it was reported as lagging but, upon further investigation, the internal audio (system) was not available - not an option for the Mac to utilise. Only the AirPlay devices were listed.
The process showing at ~99% was 'coreaudiom'* but on the Mini the process is 'audiomxd'. There is an observable difference here too. The iMac continues to use coreaudiod while logged in while the Mini only uses audiomxd while the machine is not in use - both are the prime CPU users & crating heat.
Continuing form yesterday's pursuit: the Mini does not self-heat once booted and then left i.e no logging in (duration of test ~2hrs), but will self-heat ~10-15mins after logging out and shall (almost always) continue to self-heat util logging in again. A quick use of Activity Monitor's CPU Time data in reference to ToD time provides this clue.
* Shall need to verify the iMac process name's last character tomorrow (m or d).
Lastly, an odd System Settings > Sound behaviour from the Mini: I screen-video'd non-active AirPlay devices to disappear a few seconds after clicking away form the Settings pane, only to reappear immediately upon reselecting the Settings pane. I can't upload the video so have two stills instead...
Sadly, more odd behaviours being captured rather than answers found.
I plan to raise an Apple support ticket in the next days, for both machines 'running hot' when not in use.
