Hi @Michael_Madsen,
I tested with Swossonic UA 2x2 and it works great 
An other option might be the Focusrite Scarlett 2i2 Audio Interface. It is inexpensive and got a recommendation from audiosciencereview.
Focusrite Scarlett 2i2 Audio Interface Gen 3 Review | Audio Science Review (ASR) Forum
Citation:
“Overall, I had low expectations going into this review and came out pleased. I am happy to recommend the Focusrite Scarlett 2i2 a very good budget audio interface.”
Thanks a lot - I also find Universal Audio Volt 2 attractive based on the reviews I have found. It is a relatively new interface, it looks nice and it should also be Class compliant. I have just ordered it so let’s see if it actually works in this environment…
What is realy nice is that i could use AppleMusic with my iPhone and route it via rooExtend into @jussi_laako s HQPlayer which boosts the 44,1/16 Signal up to DSD256 into my SMSL M500 MKIII. Works stable for me! So, no need to mess with cables or other stuff to feed AppleMusic and all other Airplay-capable Audio into HQPlayer. Limited to 16/44,1 Source, not too bad as Base for upsampling. What is @dabassgoesboomboom s take on this? While far from ideal, It’s afaik the easiest and painless way to upsample AppleMusic via HQPlayer. And the best: You could stay in Roon, regardless what Audiosource you feed via Airplay…
If one is using rooExtend with rooPlay and have HQPlayer: Take it for a Spin, it’s worth it!
Did you know that rooExtend also include NAA? You can connect your DAC directly to the Pi
Nice ! That’s another option to add to the list of ways to feed HQPlayer.
But since Apple Music went hi-res, I’m not more interested in bit perfect (up to 24/192) feeding into HQPlayer. Which means, supporting automatic sample rate switching (depending on the track’s sample rate)
HQPlayer NAA OS on RPi4 is supposed to support this but it doesn’t work properly with HQPlayer at the moment (static sound with sample rate changes)
You mean with the USB device functionality? With RME ADI-2 Pro it should work fine though.
Oops - yes I only meant with the RPi4 UAC2 input function.
Yep works perfect with ADI-2 connected for NAA input
Got the Zoom U-22 interface. Works as a charm with rooPlay. Much much better converter then the one in the Pro-ject DS2 USB. I’m happy now!
I saw there is also a UAC-2 interface from Zoom with 24/192. Should also work in class compilant mode (switchable at the back)
UAC-2 USB Audio Interface | ZOOM (zoomcorp.com)
I couldnt deal with the delays for now so got out my Topping Pre90 and slapped it between the Lumin XLR outputs and the active crossover inputs and ran my TT Phono Pre to the RCA on the Pre90 2 inputs can set with individual remembered volume levels and outputs to either XLR/RCA or both, and for the TT analogue all the way. But I still have to have the Lumin playing to trigger on the amplifiers…manageable at least.
Yes I miss out on the roon DSP and Convolution correction option but I don’t use that now so don’t miss it
Thanks for the opportunity to test it @DrCWO and use most of the other rooExtend options anyway.
Will maybe revisit this when I have a new RME ADI Pro 2/4 with support for trigger out and the delay issues are potentially worked around.
actually not sure why I didn’t use this Pre90 here before…certainly small enough. I could even use rooExtend and Roonbridge with the D90SE as a stack too and move the Lumin elsewhere…too many choices is a blessing and a curse sometimes 
Funny enough for me the delay is okay.
Got the turntable in the back room so when i’ve walked back to the sitting room the music starts in time 
Got the Universal Audio Volt 2 interface. It also works as a charm with rooPlay. Much much better converter then the one in the Pro-ject DS2 USB so I’m also happy now!
The only challenge now is that I still have to reboot Roon now and then after I change the sample rate for instance to get rooPlay and rooDial to work as intended again.
Please explain exactly what you want to achieve and what you have to do that it works. Do you use the Volt 2 also as a playback device?
I only use it as an input device for an analog source (vinyl). The same happened with the Project phono preamp with build in ADC. I doesn’t matter if the sample rate is changed at the Extend setting page or in the URL line in the radio station setup. Often the sample rate “defaults” to 44.1 kHz even if you change and save from192 to 96 kHz for instance. Everything looks right but the stream is silent/empty until next reboot of Roon core running on a NUC computer. Sometimes it won’t even start the stream at at all. It seems to be some kind of a “handshake” issue between the Raspberry and the USB source, but I don’t understand why a reboot of Roon can solve it but it actually does…
The same happens if the USB source is switched off and powered on again. Maybe the on/off command for the ADC you are planning can solve the issue?
@Michael_Ashwell I just received today the Hifime S2-Dig (optical → USB) . Uptill now no audio interface pops-up in the “extension menu” (see pictures). My CD drive works fine with RooPlay. Can you make a picture of your “extension menu” and share it ? Or @DrCWO ca you help me out?
As a remark:
I check my Hifime S2 Dig by connecting it to my PC and device work till 192khz 32 bit so expect Hifime S2-Dig is ok.
All I get on the TV is Roon plus a ?
I tried restarting the PI but the same.
RooPlay is working and I just streamed a song from my iPhone to Roon using it. Nice!
Any suggestions how to get album art on the TV?
Also, makes sure that you have “rooPlay” properly specified as the name of your rooExtend Box in your rooExtend extension settings. exact case is important.
You just do the same as for all TV output 
Open the volume slider, click the TV-Symbol above the slider
And next in the Display settings click on “Display now” in the “Chrome” compartment.
Reading this after my PM to you.
As far as I understand the description here Hifime S2 DAC - USB and Optical DAC for iPhones, Android, USB-C (hifimediy.com) the HiFime is a DAC! Yes it has a Toslink input but this is not made for recording.
It is made for being connected to the Toslink output of a TV or CD player and then converts this to its analog output.
I think you can’t use this device as an input for rooPlay 
Best DrCWO
