14 Jan 2026
Current setup:
Mac Studio with 4x monitors:
- Dell via USB-C
- Dell via USB-C
- Elgato prompter via DisplayLink Manager
- Demo monitor (1080p native) via HDMI splitter (other split output goes to ATEM Mini)
Camera:
- Blackmagicdesign Pocket Cinema Camera 4k, with Rode XLR microphone connected to it
- HDMI output from camera into ATEM Mini Camera 2
ATEM Mini
- Camera 1 input = Blackmagicdesign Pocket Cinema Camera
- Camera 2 input = HDMI output from HDMI splitter (Demo Monitor)
MOTU M2
- used only as DAC
- USB-C input from Mac Studio
MARANTZ K.I. Pearl Lite (Hi-Fi Power Amplifier)
- used as Power Amplifier, ingesting from MOTU M2 via RCA
What I'm trying to achieve:
Output from ATEM Mini should be PIP with Demo Monitor as background, including audio from computer, with PIP of Camera 1 input also including audio.
17 Jan 2026
Setup to demo Kaltura Avatars:
1) in Audio MINI Setup.app on macOS, create a new Multi-Output device, which sends audio both to the MOTU (for me to hear) and to the Demo Monitor via HDMI (for capture via HDMI into the ATEM Mini)
2) set the macOS system-wide sound output (under Settings > Sound) to this Multi-Output device
3) ATEM Mini:
- Demo Monitor as background video (Cam 2) + Audio ON
- PIP Camera ON + Audio (Cam 1) ON
requires HDMI splitter (see setup above) to both feed Audio & Video in the demo monitor and the ATEM Mini.
20 Jan 2026
Issue now when playing any video (Kaltura, Microsoft, Youtube) - Media Stream Error.
It seems the issue might be me using an "Multi-Output Device" setup in "Audio MIDI Setup" and selected as Output under Sound? ✅ (do not select the Multi-Output Devide as system output in Sound, only in Teams)
20 Jan 2026
This is expected behavior on macOS. Your configuration is correct, but the assumption is wrong.
Aggregate Device ≠ mirrored output.
⸻
Why you hear M2 but not BMD HDMI
An Aggregate Device:
• Combines devices into one large channel set
• Does not duplicate audio across sub-devices
• Apps must explicitly route channels 1–2 vs 3–4
macOS does not auto-mirror audio to all subdevices.
Right now:
• App sends audio → channels 1–2
• Channels 1–2 = M2
• Channels 3–4 (BMD HDMI) receive nothing
So BMD is silent by design.
⸻
Your 3 real options (pick one)
✅ Option A — You want MIRRORED audio (same sound everywhere)
Use Multi-Output Device, but never as system output.
How
• Audio MIDI Setup → create Multi-Output Device
• Devices:
• M2 (master, drift OFF)
• BMD HDMI (drift ON)
• Use it only inside OBS / Zoom / specific apps
• System Output stays M2
✔ Mirrors audio
✔ Works
❌ Cannot be system output (as you discovered)
⸻
✅ Option B — You want PRO routing (best practice)
Keep Aggregate Device, but route correctly.
In the app (OBS / DAW):
• Route:
• Output 1–2 → M2
• Output 3–4 → BMD HDMI
macOS will not do this for you.
✔ Most stable
✔ No browser breakage
❌ App must support channel routing
⸻
✅ Option C — You want “it just works”
Use Loopback or Audio Hijack.
Flow:
• System Output → M2
• Loopback duplicates → BMD HDMI
✔ Zero AVFoundation issues
✔ Zero channel math
✔ Safari / Chrome / Teams safe
❌ Requires Rogue Amoeba tool
⸻
What you should NOT try
❌ Expect Aggregate Device to mirror
❌ Set Multi-Output as system output
❌ Add HDMI displays as clock masters
Option A is exactly what you should use for Microsoft Teams 👍
With one important constraint.
⸻
Short answer
Yes, use a Multi-Output Device
No, do NOT set it as macOS System Output
⸻
Why Option A works for Teams
Microsoft Teams:
• Captures app-level audio
• Does not rely on browser AVFoundation playback
• Is tolerant of Multi-Output Devices when selected inside Teams
Your earlier failures happened because the Multi-Output Device was set as system output, which breaks browsers and video playback — not Teams itself.
⸻
Correct setup (do this exactly)
1) Create / verify Multi-Output Device
In Audio MIDI Setup:
• Devices:
• ✅ MOTU M2
• ✅ BMD HDMI
• Clock:
• M2 = master
• Drift correction = ON for BMD HDMI
• Sample rate: 48 kHz
Do not include displays, mics, or extras.
⸻
2) macOS system sound (critical)
System Settings → Sound → Output
• ✅ M2
• ❌ NOT the Multi-Output Device
⸻
3) Microsoft Teams settings
Teams → Settings → Devices
• Speaker:
• ✅ Multi-Output Device
• Microphone:
• Your usual mic (NOT part of the Multi-Output)
⸻
What will now work
✅ Teams demo audio
✅ HDMI monitor sound
✅ Your headphones / speakers
✅ Browsers (since system output is M2)
✅ Kaltura / SharePoint playback
⸻
What to avoid
❌ Selecting Multi-Output as system output