XPS 8950, Focusrite Firewire PCI card?

You will have to disable the onboard Realtek HD Audio in Device Manager and change the Output setting on the Win 10 Sound screen accordingly.

Your PC comes with Waves MaxxAudio Pro software installed as the sound controller. So you probably will have to disable or uninstall Waves because it may not be compatible with Focusrite. 

After installing the legacy 1394 firewire driver, the system crashes, however the card and current driver appear - XPS 8950 seems to not like the legacy firewire driver?

I had a firewire PCIe 400/800 card running in Win 10 with the default Windows driver.  It was a T.I. firewire chipset card, what Focusrite and most other recording interfaces want to see.  My MOTU interface was dual firewire/USB and worked equally well with either interface so I dumped the firewire.

The Legacy driver went away early in Win 10.  As noted, the current default firewire driver works without the old issues that required the Legacy driver.

I can't say if there are any issues with Win 11 as my current MOTU interface is USB C interface,

If your Focusrite unit is causing the problem, first verify the firewire card is the T.I. chipset.  I had a Focusrite Saffire Pro 40 and it would only work or work properly with a T.I. chipset card.

If you only use the Focusrite for recording operations and not regular PC audio you don't need to disable Realtek.  Disabling Realtek is only needed if you use the Focusrite for all PC audio.

Guess you've answered your own question.

Have you contacted Focusrite to ask if they have a Win 11 driver for your model audio controller?

Thanks everyone for your ideas!

I'm running system 10 but apparently Focusrite doesn't have legacy drivers for the old Saffire interface. The system seems to recognize the current 1394 PCI card, but no driver is present for the Saffire - anyone aware where these can be downloaded?

I'm just using the interface for audio production, no need for the Realtek drivers....

Many thanks!

Sadly on the Foucrite site they ceased providing drivers for the old Saffire interface,  so I don't have the installer. 

Mind you I do have functional drivers in my old system using this interface, wonder if it's possible to transfer them to win 10?

The Focusrite site is the place for any available drivers.  If no later drivers are available, install them in a compatibility mode for older Windows.  That works many times.

What I was referring to with Realtek.  No need to disable them.  I have Realtek enabled on my recording studio desktop and use Realtek audio for PC use OTHER than recording.  Configure your recording program to use the Focusrite.  

Sadly mine isn't listed - I've got the old original Saffire (the white desktop model)

Can't seem to locate drivers anywhere for the old beast!

What Focusrite model do you have?  Drivers must be "installed" so copying them are out.

I see the control programs listed for the Saffire Pro 40.  If that is what you have, install the control program  and see if it also contains the drivers.  Many times it does.

I got my Saffire Pro 40 back in the Vista era.  

Post what you are looking for on some of the recording forums such gearspace (used to be gearslutz).

Gearspace.com - Gearspace.com - The No. 1 Website for Pro Audio

Also, contact Focusrite support as they may have a driver that's not posted.  

It should be possible to install a Firewire 400 PCI card on your Dell XPS 8950 running Windows 10, but it's important to check for compatibility with your specific hardware and software. You may also need to install drivers for the Firewire card and audio interface to ensure proper functionality.