How to Revive Old FireWire Interfaces With the RME Digiface USB

How to Revive Old FireWire Interfaces With the RME Digiface USB

If you have a FireWire audio interface sitting in a closet because your Mac no longer recognizes it, this video is for you. Apple dropped FireWire support years ago, and since then a lot of perfectly good gear has ended up collecting dust — interfaces with quality preamps, multiple headphone outputs, and features that would cost significantly more to replace than they did originally. In this video I show you how I brought three older interfaces back to life using the RME Digiface USB, and ended up with more inputs, more outputs, and more headphone mixes than I had before.

The Gear and the Problem

My main interface for years has been an M-Audio ProFire 2626. I bought it well over 15 years ago and had it modified by BLA Audio. It has eight built-in preamps, two headphone outputs, and four additional outputs I can use for monitors or a headphone amp. The problem is that it's no longer recognized by my Mac at all. My laptop and Mac Mini both ignore it entirely.

I also have a MOTU 8Pre and a MOTU 896mk3. The MOTU devices do currently work under macOS 15, but the 8Pre requires a chain of four adapters to connect — FireWire 400 to FireWire 800 to an older Thunderbolt to a newer Thunderbolt port. It works, but it is not elegant. More importantly, every time I start up my Mac I get a message from Apple warning that the existing software extension won't be supported in future versions of macOS. So even though they work today, they could stop working at any time.

The previous solution was to use the MOTU 896mk3 as my main interface and connect the ProFire 2626 and 8Pre into it via ADAT as expanders. That gave me 24 inputs, which worked well for the Camaro 67 recording sessions. But I could never get the outputs of the ProFire routed correctly in MOTU's CueMix software. So despite having a ProFire with two headphone outputs sitting right there, I could only use the single headphone output on the 896mk3. Plenty of inputs, not nearly enough outputs.

What the RME Digiface USB Actually Is

The RME Digiface USB is a small, simple unit. There are no microphone preamps on it at all. The only physical output is a single headphone jack with no volume knob. What it does have is four banks of ADAT, and each bank can send and receive eight channels of digital audio. That means you can connect up to four ADAT-capable interfaces to it simultaneously and have all of their inputs and outputs available through one USB connection to your Mac.

At the time of this recording the Digiface is priced at $629 USD. For context, a comparable new interface with 24 inputs would cost considerably more and still wouldn't give you the routing flexibility that comes with Total Mix FX. A big thank you to Peter at GerrAudio, the Canadian distributor for RME, for loaning me the unit to test.

How I Have Everything Connected

Each of the three interfaces connects to the Digiface via ADAT cables. One ADAT cable carries eight channels in one direction, so you run a cable from the ADAT output of the interface into the ADAT input of the Digiface, and another from the ADAT output of the Digiface back into the ADAT input of the interface. Do that for each interface you want to connect.

In my setup the inputs are mapped as follows: channels 1 through 8 are the M-Audio ProFire 2626, channels 9 through 16 are the MOTU 896mk3, and channels 17 through 24 are the MOTU 8Pre. That gives me 24 preamps total in Logic Pro, all visible as inputs through a single USB connection.

On the output side, the ProFire's eight outputs are fully accessible, the 896mk3's eight outputs are fully accessible, but the MOTU 8Pre is a different story — when it's running in optical expander mode, the physical outputs including the headphone output are not available. Each input is hardwired to its corresponding ADAT output and that is all you get from it. Worth knowing before you buy if the 8Pre's headphone output is something you were counting on.

Clock Sync — Get This Right First

Before you touch any routing, you need to get the clock sync sorted. If the interfaces aren't locked to the same clock you will hear clicks, pops, and dropouts, and it will be obvious immediately.

The Digiface acts as the clock master. In the Fireface USB settings, set the clock source to Internal and choose your sample rate — I work at 48kHz. Every interface connected to it then needs to be set as a slave, receiving its clock from the ADAT connection coming in from the Digiface.

For the MOTU 896mk3, you set the clock source to Optical A in CueMix. The MOTU devices can have their settings changed directly on the unit itself, which is very convenient — you don't need a computer connected to adjust them. The M-Audio ProFire is less flexible on this front. Since it's not recognized by my current computers at all, I can't open its software to change settings. Fortunately I had already configured it years ago with the sample rate set to 48kHz and the clock set to receive from ADAT, so it just works. If you need to change settings on an older unsupported interface, you may need to find a computer running an older OS that still recognizes it.

When everything is synced correctly, the Digiface shows solid green lights. If something is off, the lights flash — either the cables are reversed, the sample rates don't match, or the clock isn't set correctly on one of the interfaces.

Routing With Total Mix FX

This is where the Digiface earns its money. RME's Total Mix FX software gives you complete control over every input and output in the system. You can see all 24 hardware inputs, all the software playback channels coming from Logic Pro, and all your physical outputs laid out in one interface.

For my setup: main monitors are assigned to outputs 5 and 6 of the ProFire. Headphone outputs 1 and 2 are on ProFire channels 1/2 and 3/4. Headphone 3 is on the MOTU 896mk3's headphone output, which maps to channels 9/10. Headphone 4 is the Digiface's own headphone output. And then I have a PreSonus HP4 connected to ProFire outputs 7 and 8, which gives me four more headphone outputs.

The result: five dedicated headphone mixes. One for each of the first four outputs, and a shared mix for the four outputs of the PreSonus HP4. That's a significant upgrade from the single headphone output I had before.

Creating individual mixes for each headphone output is straightforward in Total Mix FX. You select which headphone output you want to configure, then bring up whichever inputs you want that person to hear and set their levels independently. Switch to a different headphone output and you get a completely clean slate to build a separate mix. This is exactly the kind of monitoring flexibility you need when tracking with multiple musicians.

One note on the Digiface's own headphone output: since there's no physical volume knob on the unit, you control the headphone level through the software slider in Total Mix FX. There is a mobile app for Total Mix FX as well, so you could run it on a phone or iPad and keep it on your desk rather than opening the full software every time.

Why I Prefer the ProFire 2626 as the Main Interface

One of the things I appreciate most about having the Digiface in the setup is that it finally lets me treat the ProFire 2626 as my main interface again, with full access to all its outputs. And there are a few reasons I prefer it over the MOTU 896mk3 for that role.

The two headphone outputs are the obvious one. But the input behaviour is worth explaining too. When you connect a TS or TRS cable into the back of the ProFire instead of an XLR, it automatically switches to line level mode and disables the internal preamps. That means if you're using external preamps, the gain knob on the interface does nothing at all. The gain is coming entirely from your external preamp, which gives you a cleaner signal path and no interference from the internal electronics.

On the MOTU 896mk3, plugging in the same cable doesn't disable the internal preamp. You have to manually turn the gain all the way down and engage the pad before boosting with your external preamp. It works, but it's more steps and more potential for error. The ProFire's approach is just cleaner for anyone who regularly uses external preamps.

Final Thoughts

After spending a few weeks with the RME Digiface USB I'm seriously considering buying one. It has done exactly what I hoped — revived my M-Audio ProFire 2626, integrated all three interfaces into a single USB connection, and given me routing flexibility I didn't have before. RME has a strong reputation for driver stability, and as long as they keep supporting the Digiface, this setup effectively future-proofs the gear I already have rather than forcing me to replace it.

The one thing I wish it had was a physical volume knob for the headphone output. Using a software slider is workable, especially with the mobile app option, but a hardware knob would have been a nicer touch.