RME has added a Class-Compliant mode to its powerful audio/MIDI interface Fireface UCX. The class compliant mode (CC mode) allows the device to work natively under all operating systems including Linux. Despite the fact that historically, RME offered good Linux support (Hammerfall DSP series of cards), let us not be fooled when it comes to RME’s intentions. The CC mode was not introduced with Linux users in mind. Its primary purpose was to ensure that it plays nicely with iPads. The Linux support is more of a by-product of the USB class compliance mode.
Now although the Fireface UCX is perfectly usable and still very powerful in the CC mode, it does not come close to what the device has to offer with the proprietary RME drivers available on Windows or Mac. One of the biggest things missing in the CC mode is TotalMix, a mixer providing a comprehensive set of effects and a limitless routing capabilities (image below):
On Linux, by contrast, the device mixer boasts as many as one channel to adjust, namely “Speaker Volume”. Sad.
Being in the CC mode, the device is recognised in Slackware 14.1 out of the box:
[ 6.327198] usb 1-3: New USB device found, idVendor=0424, idProduct=3fb9
[ 6.327303] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 6.327405] usb 1-3: Product: Fireface UCX (23673729)
[ 6.327504] usb 1-3: Manufacturer: RME
[ 6.327600] usb 1-3: SerialNumber: xxxxxxxxxxxxxxxxx
0 [PCH ]: HDA-Intel - HDA Intel PCH
HDA Intel PCH at 0xf7a30000 irq 47
1 [MID ]: HDA-Intel - HDA Intel MID
HDA Intel MID at 0xf7a34000 irq 46
2 [UCX23673729 ]: USB-Audio - Fireface UCX (23673729)
RME Fireface UCX (23673729) at usb-0000:00:14.0-3, high speed
To conclude, it is indeed great that this powerful device works under Linux. It’s a pity that its capabilities in the CC mode are somewhat limited.