Hello, I was able to install the sound card successfully. Unfortunately, when the sound is played back from the speakers, it comes out with a lot of scratching. Can you help me to fix it?
Hey Matthias, did you manage to get the on-board microphones working?
For me sound output is very clear on a brand new RPi4 / Raspberry OS (32bit, lite) but microphones only record a flat line (nothing) 
Did you test the output via aplay or some other software?
Hi Flo,
did you try to apply the presets as explained in the installation guide?
Yes, I’ve tried about every configuration possible, I’ve even tried everything with and without Raspbery Pi OS desktop (desktop image + lite image).
After several hours I’m about to give up now 
For sure the ULTRA+ is working wiht the last destop image, many boards are sold every day and sucessfully installed. All boards are also tested in the factory for the microphone.
BUT it could happen that a board is defective, so please ask a replacement @ Amazon.
sorry for the trouble