Hi there! Sorry to hear you're having trouble with TonalEnergy crashing when using Bluetooth headphones on your Mac. Let's work through this together to get your app running smoothly.

To start, could you tell me a bit more about the crashes? For example:
- Does the app crash immediately when you connect the Bluetooth headphones, or after you start using the tuner/metronome?
- Are your Bluetooth headphones connected and working fine with other apps on your Mac?
- Have you tried restarting your Mac or the app already?

Meanwhile, here are some steps tailored for your Mac OS X 10.15.7 to try:

1. Restart your Mac and Bluetooth headphones
Sometimes a simple restart can clear odd glitches. Turn off your Bluetooth headphones, restart your Mac, then reconnect the headphones and try the app again.

2. Check Bluetooth Connection Quality
On your Mac, click the Bluetooth icon in the top menu bar and ensure your headphones show ‘Connected’. If multiple devices are connected, disconnect all but your headphones.

3. Update TonalEnergy App
Make sure your TonalEnergy app is updated to the latest version available from the App Store, as updates often fix compatibility issues.

4. Reset TonalEnergy Preferences
Sometimes app settings can get corrupted, causing crashes. You can try deleting TonalEnergy’s preference files:
- Open Finder and go to ~/Library/Preferences/
- Find files named like com.tonalenergy.*.plist and move them to the Desktop (to back them up)
- Restart the app to allow it to create new preference files.

5. Test with Wired Headphones or Internal Audio
Try using the app with wired headphones or Mac's internal speakers. If it works fine, the problem is likely Bluetooth-related.

6. Check for Mac OS Updates
While you're on 10.15.7 (Catalina), ensure all pending system updates are installed, as sometimes OS fixes improve Bluetooth stability.

If these steps don't help and the app keeps crashing only with Bluetooth headphones, it might be a compatibility issue between TonalEnergy and your specific headphone model or Bluetooth driver on macOS Catalina.

Would you be able to test with a different Bluetooth headphone or speaker if possible? Also, if you can share the headphone make/model, that might help narrow down the issue.

Let me know how these go or if you've already tried any of these steps!