Linux Support At Last

EVGA have released limited support for the Nu Audio (not Pro) under Linux.   It's pretty bare-bones, but it's enough to allow enjoying the quality of the Nu's hardware and design without needing Windows.  A little background:  internally the Nu is constructed as a USB audio device and an USB-to-PCIe bridge, on the same module.  Linux kernel has supported USB 2.0 audio devices for years, and as of kernel 5.4, even has a special tweak so that the EVGA Nu is recognized as DSD capable.  None of the enhanced functions (Nahimic audio EQ, sound tweaks, etc.) are available in Linux.  Support is, as I say, bare-bones.

Windows Still Needed

There is one hitch:  the EVGA Nu requires different firmware under Linux, and as of this writing, firmware can only be changed under Windows.  At least temporarily, install the card in a Windows system and install the normal EVGA driver and utility.  This is important - several settings must be made under Windows, before moving the card to Linux.  A few things to tweak:

• Lighting Effects:  if you want to use any of the Nu's cool lighting features, or just to turn them off, do that using the Windows utility.
• Output:  the Nu Utility allows you to select line out, headphone, or both outputs.  This cannot be done under Linux, so click to activate both of them.
• Volume:   The Nu has two volume controls.   The main one controls the output level from the Digital Analog Converter (DAC).  The second is an analog control that works for line and headphone outputs.  Use the headphone volume to crank the headphone output to or near the highest level.  This also cannot be changed under Linux.

The good news is, these tweaks are retained by the Nu through firmware reflashing and between system restarts (like from Windows to Linux.)

Firmware Update

Operating under Linux requires different firmware from the current Windows drivers.  EVGA makes Linux firmware available here:  https://cdn.evga.com/nuaudiocard/NU_Audio_FW_for_Linux.zip  Download and unzip the firmware files and firmware update program under Windows.   The download archive includes a PDF describing the process. and I found the firmware update process to be straightforward.  There are two firmware versions: 

• EVGA_Audio_XMOS_20200515_Ver0x001_Linux_MinIn_DFU_IS25LP016D.bin  installs with Microphone input active
• EVGA_Audio_XMOS_20200515_Ver0x002_Linux_LineIn_DFU_IS25LP016D.bin installs with Line input active.

There is no mechanism to switch from mic to line input once running under Linux. 
After firmware update, restart the system under Linux.   I think the settings will also be retained if you have to move the Nu to a different computer.

Under (Ubuntu) Linux

First check to make sure the Nu is seen and active.  Open a terminal and run alsamixer.  Push F6; the Nu should be listed - select it.  Initial volume level is low, and increasing the volume using the Pulseaudio volume control doesn't help.  You must use alsamixer from the CLI to set levels at 100% (see attached screenshot)  According to EVGA, only the "PCM Front" control is active.  It feeds that analog section mentioned above.  Set it to the maximum level, then use the Pulseaudio volume control to set volume to a comfortable level.   If you use the Nu for recording, push F5 and confirm "Line" or "Mic" matches the firmware you've loaded above.   Set the record level at 100%.
At this point, you're ready to enjoy the EVGA Nu's quality sound for playback under Linux.  If you intend to use the Nu for recording, read on.

Recording

I use my Nu for audio recording - I remaster old vinyl for fun and self-torture.  Here are a few quirks I've found.

• PulseAudio:  Pulse reports the Nu as a 4.0 channel card.  It's not.  
• PulseAudio sampling:  in Ubuntu, Pulse initializes the card and sets the recording sample rate and type.  To change the default, edit /etc/pulse/daemon.conf.  I've set mine to 192KHz/32bit format, like this:

default-sample-format = s32le
default-sample-rate = 192000
alternate-sample-rate = 48000

 

• Sample rates above 192KHz:  on Line input, the Nu employs an excellent ASMedia Analog/Digital Converter (ADC) supporting sample rates up to 384KHz.  At rates above 192KHz, however, the ADC's internal DC-offset filter is disabled.  This results in odd behavior like level meters being permanently pegged at a high level.  It also means you'll need to manually remove DC offset from recorded files using a suitable post-processor.
• Audacity:  I struggled quite a bit with Audacity under Ubuntu.  The package installed from the Ubuntu software/snap store is not the most current version.  Even worse, it does not allow direct access to the Nu hardware through Alsa.  Instead, recording happens through pulse.  IMO, this is not a satisfactory solution because it inhibits Audacity's abilty to change the recording parameters.  Instead, consider installing the latest Audacity package for Ubuntu from this page https://launchpad.net/~ubuntuhandbook1/+archive/ubuntu/audacity
  Once installed, edit the launcher/shortcut or invoke from CLI like this: 
  

  pasuspender -- audacity %F

  
  This suspends pulseaudio while audacity is running, giving Audacity complete control of the audio chain.  Select the Nu as input and output devices.  Invoking Audacity this way Audacity to set the sample rate, bit depth, etc.  Watch the output volume - you'll need to control it inside Audacity, since Pulse is suspended.

Conclusion

I hope this guide is helpful to those of us who don't live in Windows every day.  The Nu is a great product.  I hope EVGA continues to enhance support under Linux.  My thanks to Lee at EVGA and the people over at audiophilestyle.com, whose efforts made this whole thing come together.
 

Thanks for the Guide

Cool GTX
Thanks for the Guide

Please share your experiences, especially if there's room for improvement.  This is a work in progress for all of us, I think.

Will I be able to use it in both windows and Linux(dualboot)

simersby
Will I be able to use it in both windows and Linux(dualboot)

sorry for the delay ... had to release your post from filter
 
as each OS is a separate boot  - I do not see why it would cause issues

simersby
Will I be able to use it in both windows and Linux(dualboot)

Short answer - yes!
Long answer - yes!  I do this, also.  When you boot into Windows after running Linux, the EVGA Windows driver will notice the Linux firmware on the card.  You'll be prompted to close all audio applications and update the firmware to match the Windows driver's expectation.  Before you shut down and boot to Linux, you'll need to use the stand-alone updater described above, and flash the Linux software back onto the card.  I've done this multiple times with no ill effects.

Cool GTX

simersby
Will I be able to use it in both windows and Linux(dualboot)

sorry for the delay ... had to release your post from filter
 
as each OS is a separate boot  - I do not see why it would cause issues

No worries.
Thanks for your answer, I appreciate your help with Linux support, we need it.
My question: is changing the firmware(microcode) will let me continue to use Nu Audio with Windows? Or I need to have 2 different firmwares for Linux and Windows?

tigerdognew

simersby
Will I be able to use it in both windows and Linux(dualboot)

Short answer - yes!
Long answer - yes!  I do this, also.  When you boot into Windows after running Linux, the EVGA Windows driver will notice the Linux firmware on the card.  You'll be prompted to close all audio applications and update the firmware to match the Windows driver's expectation.  Before you shut down and boot to Linux, you'll need to use the stand-alone updater described above, and flash the Linux software back onto the card.  I've done this multiple times with no ill effects.

Thanks for your guide and fast answer. Having this option is a good sign. I hope EVGA will make some native apps and drivers for Linux.
Again, thanks!

How high should i do the Main Volume for the DAC? Zou have only specified the headphone volume.
 

Under Windows, I have tried the DAC main volume at 80% and 100%;  I don't notice any real difference when I move to Linux.   I think the DAC digital output is controlled by Alsa under linux, so maybe this setting has no impact at all.  A 100% correct answer needs to come from someone from EVGA who has detailed knowledge of how the Linux firmware operates.