The description is a bit vague and possibly wrong:

You say that you are using a coaxial output on your Sonar Essence card and connect it to the optical ADAT/SPDIF input?
This is impossible, you can not directly connect a copper output with an optical input.

If you are using the ADAT input on your ADI-2 Pro with a TOSLINK cable, then you will also have to use the optical output of your Asus soundcard (optical SPDIF, not coaxial SPDIF which is copper based). Most likely the settings of your Asus card are wrong and leading to the wrong output or the Asus adapter for optical SPDIF is damaged.

Are you using the ADI-2 Remote application? Then you could post a screenshot of your ADI-2 settings.
A screenshot of the Asus Xonar settings will also be helpful.

Are you aware of the other screens of your ADI-2 Pro FS R BE?
The State Overview will support you troubleshooting digital connections.

Recommendation: if your mainboard should also have an optical SPDIF output to connect the ADI-2 Pro FS R BE via TOSLINK cable, then I would use this one from the mainboard and remove the Asus card from the system.
The ADI-2 Pro is actually too good to modify the digital audio signal with any DSP tools from Asus before conversion.
At least I would use neutral settings in the Asus card so that the lossless audio signal is passed through unaltered.
Then you can also use the "Bit test" to validate lossless transfer of digital audio data up to the DSP of the ADI-2 Pro shortly before the D/A conversion takes place.

You only need a digital connection from PC to the ADI-2 Pro FS R BE to connect the reference converter for "lossless" audio transfer.

In terms of quality and jitter: digital connection is lossless and SteadyClock FS is designed to remove any potential jitter from any digital input signal including USB.

Hi guys,

Thank you for your feedback.

ramses:  The cable I was referring to looks like this:
https://www.amazon.ca/TNP-Premium-Tosli … I9FPU?th=1

The long end goes to the Asus soundcard, and the square part to my ADI 2 unit.

Here is the screen shot of both applications as you advised, as well as my default playback: https://www.dropbox.com/scl/fi/by44vqj7 … j&dl=0

I wasn't aware that there's an app available for the ADI 2. I used this DAC back in 2021, and just now reconnecting it.  Previously I had HD6xx which didn't sound any different to my Asus soundcard vs this unit, now I have Focal Massdrop ed, and the difference is day and night with ADI 2 vs Asus soundcard. 

I guess I can make EQ presets on this app now, so wouldn't really require connection to my pc soundcard.  But I'm still curious to have it working, because it used to work previously, now for some reason I can't make it play while both those devices are connected.  Also, I did not try fiddling with any settings on the device itself, I just thought it would simply play without having to tweak any settings, as I recalled it being quite tedious with just few buttons on the dac for lots of settings.

Btw, are there any available presets I can upload to my app for things like music/gaming/movies/hifi etc?

Thank you,
sk

Here's the Device tab, and SOV (state overview?): https://www.dropbox.com/scl/fi/816y5sta … f&dl=0

The PCM/SPDIF do not have any other settings as far as to my knowledge.  I do vaguely recall, when I had my monitors connected, I did have to click on SPDIF Out on Asus app, next to the PCM to make it work.

link edited

Hi KaiS,

Thank you for troubleshooting this with me.  Yes, it did work with those above steps that you described.  My startup display was USB mode and balanced phones active so I changed it to DAC mode.

Now a little trouble that I'm having is that the sound is still generic as I was getting through ADI DAC previously, when I click on different presets on Asus app, such as Music/Gaming/HiFi, etc, it is not changing anything whatsoever. 

If I connect my headphones directly to Asus sound card, of course the sound profile changes entirely with clicking on each preset, and same happened when I used to have monitors connected to ADI 2, whenever I changed the preset on Asus app, it completely modified the sound, unfortunately, that is not working with my headphones.  Please let me know any additional suggestions you guys may have.

On ADI 2 app, there's option to load presets, are there any such files available to download?

Please see "ADI-2 Remote" manual ch. 2.

Connection
Under the hood the ADI-2 Remote uses a USB MIDI port to communicate with the hardware device. The connection is the same as usual – via USB 2.0 to a Windows computer, a Mac com-puter, or an iPad.
When everything is connected and up to date, but the app’s title still says Disconnected: check that the MIDI Control option is set to ON (menu Device Mode for ADI-2 Pro and ADI-2/4 Pro, Remap Keys/Diag for ADI-2 DAC).