Record your microphone and system sound simultaneously

 To record your microphone and system sound simultaneously, you need to combine your physical microphone and BlackHole into an Aggregate Device.

1. Create the Aggregate Device

• Open Audio MIDI Setup on your Mac.
• Click the + button in the bottom-left corner and select Create Aggregate Device.
• In the panel on the right, check the box for your Microphone (e.g., MacBook Pro Microphone or USB Mic).
• Check the box for BlackHole 2ch.
• Check the Drift Correction box next to BlackHole 2ch.

2. Check the Subdevice Channels

• Look at the Subdevices list at the top of the window.
• Note the channel numbers assigned to each device (e.g., Channels 1-2 might be your microphone, and Channels 3-4 might be BlackHole). You will need this for multitrack recording apps.

3. Keep Multi-Output Device Selected

• Ensure your system audio output is still set to the Multi-Output Device you created earlier (System Settings > Sound > Output). This ensures system sound feeds into BlackHole.

4. Configure Your Recording Software

• Open your recording app (e.g., GarageBand, OBS Studio, or Audacity).
• Set the input device to your new Aggregate Device.
• If using OBS, add two separate audio input sources within the mixer: one mapped to your mic channels and one mapped to the BlackHole channels.
• If using QuickTime, it will record all channels at once into a single file.

Are you using a specific recording software like OBS Studio, GarageBand, or Audacity? I can give you the exact steps to separate the mic and system sound onto different tracks in that app.