I'm sorry for the bad news, but it is the new system files protection in OS X 10.11 that breaks the EMU USB 0404 driver and EMU will NOT update the driver because of the END OF LIFE status of the product. Here's their reply to my question:
"""
Thank you for contacting E-MU support.
We are sorry to inform you that we no longer have further upgrades, software updates, and drivers for our End of Service Life (EOSL) products.
The E-MU 0404 USB has been classified as one of the EOSL products, and the last driver update we have for this product is for OS X Snow Leopard and OS X Lion.
You may want to consider to use your Time Machine Backup to downgrade your Mac to a lower OS X version so that your device can work again.
Cheers,
Yisong Chen(YS)
E-MU Systems
Technical Support Group
"""
It drives me mad, because all they need to do to make it work again is SIGN the driver....