I just worked through all this over the weekend. Initially I thought the installation had failed for me, but there were a couple of vital little steps i'd overlooked from earlier comments. I'm on Sonoma 14.6 and have an Onyx 1640i working perfectly again with a Macbook Pro M1. Here's a summary of the steps I followed which are all collated from numerous posts throughout this thread, hopefully this might help someone. Thanks to everyone who has contributed to this thread to get this fix working! Installation Restart computer in Recovery mode. Launch Terminal from the Utilities menu. Disable SIP by running the command:  csrutil disable Utilities > Statup Security Utility > Security Policy Permissive Security > Allow user management of kernel extensions from identified developers > OK Reboot computer Install AppleFWAudioVentura.pkg to install the kext file Fix file permissions: sudo chown -R 0:0 /Library/Extensions/AppleFWAudio.kext/ Manually load AppleFWAudio.kext: sudo kmutil load -p /Library/Extensions/AppleFWAudio.kext You should now be prompted to allow the kernel extension in System Settings System Settings > Privacy & Security > Allow Restart (will reboot twice) FireWire device should now be working

 Optional (re-enable SIP without kext)
 Restart computer in Recovery mode. Launch Terminal from the Utilities menu. Enable SIP by running the command:  csrutil enable —without kext Warning message will display ~”csrutil: requesting an unsupported configuration. This is likely to break in the future and leave your machine in an unknown state.”. Just ignore it :) Reboot and check that FireWire device still works. If it doesn’t re-run steps 8 -12.