Unfortunately I can't give you a trick other than contact the RME support via email and send in the unit for repair, seems to be broken firewire port or internal power supply fail.
Email support : support@rme-audio.com

Great to hear.
Your task list has lots of good ideas and at the end when repaired or fixed you have a superbe audio interface.
It was the flagship a few years ago, the features and specs don't get lost.

Same problem here with an Old ff400. Tryed with my m1 on Monterrey, Ventura and Sonoma. All fails. Tryed on a pc with W10 and fw400 and the same. Just I’m waiting for a friend who has a working unit with his Mac m2 to test the last try. Then will mail for the repair costs

So good news on the issue,

Today I got a Delock FireWire controller with Texas Instruments chipset for PC (Windows 10) delivered.
First I connected the Fireface with a 9 pins to 6 pins cable and the unit was not recognized, host light on.
But when I connected the unit with a 9 pins to 9 pins cable the unit worked, which is really great news.
I then uploaded the latest firmware ( which seems to be already present ) just to be sure.

Now I know the unit works and has connection on PC which is great but I still can't get it recognized on any Mac.
So I'm back troubleshooting again to find out what's the issue here. Am I missing something ?
When I get any results I will post them here.

If anybody has any clue or tips, you're definitely welcome.

Hi Ramses,

I have no idea what kind of chipset the Delock FireWire card has, there is nothing mentioned on their website nor on the data sheet.
For now I only needed it to see if I could get a connection with the Fireface, which it does so the unit is working good.
My studio computer is a Mac so I need to get it working on a Mac which seems not possible for some stupid reason.

Ramses,

I will keep it in mind if I ever need to run it on PC, thanks for the heads up ;-)
The seller doesn't respond on any of my messages anymore so sending it back is no option.
I don't want to sell this unit either knowing it doesn't seems to work on a Mac.
In my opinion there must be a driver issue because it works on PC right away.

I don't have an extension unit so I can't test that, I have other FireWire interfaces from an other manufacturer which all work on all Macs. I will keep trying to get it working otherwise I maybe have to send it in to RME for repair, but it is a little bit fishy i.m.o. because it works on the PC why shouldn't it work on a Mac. I have emailed RME support, they asked me to test it on a Pc but I haven't heard back from them yet.

Longer time ago, but yes it was running on catalina with Firmware 2.77.

There were some problems with allowing the drivers with the privacy and security settings in the past. This is a known problem that when you reinstall the drivers the button for allowing the drivers would not show up in the security settings. Also when upgrading the OS the security could blok the drivers again. There where some work arounds to fix this problem but they didn't always work. The added permission via the terminal in the OS recovery boot was a final fix from RME to tackle this problem.

An to answer your question, as noted in the tread, I installed the recommended drivers on three different machines. Two iMacs and a Mac mini. All have a different OS with their recommended drivers, OS 10.6 - OS 10.13 and OS 10.15

I start to hate the Mac OS more and more. They work great if they work but the hardware support through drivers sucks to say at least. I have an old Digidesign FireWire interface that is only supported up to OS 10.6, then I have a Focusrite interface which is only supported up to OS 10.15 then there are a lot of Plugins that need a higher OS than 10.15 in order to work, so basically Mac OS is a big bottleneck for all devices because all the mentioned hardware and plugins work well on Windows 10. I personally think I will build me a Windows PC and have everything working on Windows 10.

When reading all this I wonder why I did not have any of such problems with my good old Fireface 800. Neither had I any problems with driver installations on a MacBook Pro (Intel) nor on a iMac M1. And I never ever had to reinstall drivers after any MacOS upgrades.

My setup is working and always worked flawlessly up to the most current situation, which is Sonoma 14.5 on the iMac M1.

BTW, are you using the original Apple adapters?

For everyone following this, I will try a clean OS install.

I was thinking, the only thing all three Macs have in common is that they had previously Focusrite Saffire drivers installed.
So I will do a clean Mac OS install on a machine and see if it solves this weird issue.

I have a hunch it will work...  (fingers crossed :-)

Done a fresh install of Mac OS 10.15, installed the (driver_fw_mac_3391.zip)
Checked the security settings, RME driver didn't show so couldn't click "accept"
Rebooted the computer and still no connection, nothing showing on the FireWire bus, host led stays red.
Rebooted into security boot, added the driver into the security settings manually, reboot... still nothing.
Checked if the driver was added in the terminal with command: /usr/sbin/spctl kext-consent list and it shows three times
Allowed Team Identifiers:
67AK2U2X7M
67AK2U2X7M
67AK2U2X7M
I don't know if this is generating a issue or not.

In the MacOS system report under thunderbolt, the adapters should appear.
If you connect the adapters without Fireface do they appear in the system report ?

After the adapters there is only the Fireface, the failure seems to be there or in the cable.
But the unit works fine on the Windows computer... weird.

Have you tried different orders to start or power up the Mac and Fireface?
In rare occasions my FF400 has to be powered off and on again to be recognised from the Mac

The firewire cable is how long ? And not rolled together, right ?

Never roll cable !

I don't get it either, I checked the firmware on Windows and it says it's version 2.77,
Flashed the bios again but nothing changed, works on Windows but not on Mac.

By the way I read from a user who had a similar problem, he connected it to a old OS had it recognised and flashed the firmware there, he had however an old firmware in the unit but it fixed his problem so I will try to hook it on a OS 10.6 machine which has a 9pin FireWire onboard and see if I can get communication there. I already tried this but I will try again.

Are you using the same FW connection on both systems (800/400)? If you're only using 800 on the Mac, try with an adapter.

Okay tested it on Windows PC again and found out that the FireWire 400 (6-pins) port on the Fireface doesn’t work. Both 800 (9-pins) ports do work. So there is something wrong with the Firewire i/o on the Fireface. For some reason this doesn’t affect the functionality on a Windows PC but it seems to screw up the FireWire bus on a Mac even when only the 800 (9-pins) connection is connected.

My conclusion is that the unit needs to have the FireWire controller replaced to work properly on a Mac.

I’ve put the Fireface in standalone mode and connected it to a Focusrite Pro40 with adat. So at least I can use the four mic pre’s for recording drums next week and have four extra line inputs available for external mic pre’s. A total of 16 mic inputs which is great.

A little bit happy after all :-)

Ports either work, or do not work (physically).

You seem to use at least two different cables:
- 1394a (FW400) to 1394b (FW800)
- 1394b (FW800) to 1394b (FW800)
- maybe a 1394a (FW400) to 1394a (FW400) too?

Would make more sense that there is sth wrong with your 1394a to "whatever" cable...?
"whatever" because, afaik, the Delock card has two 1394b and one 1394a Ports.

And at all - sure, you did 100% not use some daisy chaining connection-stuff (with your other 2 interfaces) on your FF800 during your experiments?

See Page 25 in FF800 Manual:

• The cabling of FireWire 800 units is critical. In real world operation, it is not unusual that all
Firefaces have to be connected directly to the 1394b ports of the computer, using cables of
similar length. A long cable from the computer to the first Fireface, and a short one from the
first to the second Fireface can cause problems.
You use different cables, multiple macs, each with different connection 

Maybe, keep in mind for future:
Red Light = No physical connection between host and the unit (for whatever reason).
Page 9 in Manual:

Exactly. What i meant - i am not really sure if chaos-dynamics uses the FF800's other FW Ports as a Hub for his other Devices, too. In this case the 400 Port will probably not serve enough Bandwidth plus the cable length things, etc. Because i saw some older Mac Models in his "collection" just offer one single FW Port.

Here is what the manual says:

"When using only one Fireface 800, a FireWire 800 interface does not improve performance, and does not help to achieve lower latency. But connecting a hard drive to the Fireface (Hub functionality), FireWire 800 will immediately increase performance and reliability."

I'm not sure if FireWire 800 in that case would have any effect on the performance of the Fireface or the added components (here: the hard drive) only.

In any case I would make the tests with only the Fireface connected and no other components. And with the original FireWire 400 cable that came with the unit, if possible (plus the original Apple adapters where neccessary).

And the start up sequence should be Mac first, wait until everything is fully booted, only then power on the Fireface. I never had problems with this order but in rare occasions when the Fireface was powered on first. That was at least my experience.

I was just on the phone with a technical engineer from RME and he couldn’t figure out what’s going on either. Since the Fireface gives a fault warning on the bus when connected on a Mac directly there must be something wrong with the unit. Also because other devices work when using the same system.

It’s definitely a weird issue,

I think about buying another Fireface because basic repair costs at least 250,- I can buy a used one for around 350,- and have this unit in standalone mode connected with adat, this is how I use the unit now and this works. Eventually I need 24 i/o for my setup so having more units isn’t a bad thing. I could even buy a Digiface USB and skip the whole FireWire issue.