Yes, but I still have doubts about the ASIO driver and its buffer. How is it possible that even at the maximum buffer size, the project is full of crackling during playback, whereas the same project ran perfectly on my old sound card using kX ASIO at very low buffer settings?;(

Therefore, please try all USB 2 and USB 3 ports of your computer.

Keep the driver settings window open; only then are CRC checks of the driver running.
Watch whether the USB transport errors go away (CRC errors), only 0 CRC errors are acceptable.

If this doesn't solve the issue, try another USB 2 cable (see below) and retry all USB 2 and USB 3 ports.
Also, USB3 ports can be used as they contain pins for USB2 and USB3.

I would choose a quality cable and max 3m length.
USB2 allows 5m length, but I would choose 3m max to have some additional headroom.

Don't get an overpriced USB cable over €30; this is not necessary.
For over 10 years I've had good experiences with Lindy USB cables, which are a sweet spot for me in terms of quality and price.

You will surely have USB ports for a Type B plug; then use this cable:
https://www.lindy.de/3m-USB-2-0-Typ-A-a … ;ci=800501

If you have USB-C ports on your computer, you need this one additionally (I would avoid adapters):
https://www.lindy.de/3m-USB-2-0-Typ-C-a … ;ci=800501

First of all, it's important to find "any" USB 2, USB 3, or USB-C port on your system that works. A USB port coming from the Intel chipset is preferable; a port from a 3rd-party USB controller should work as well.
This information you can get from your mainboard manual.

Regarding the extra USB PCIe card: what PCIe slot of your mainboard did you use? Ideally, mount it into a PCIe slot with PCIe Lanes coming from the CPU, but also a PCIe slot with PCIe lanes coming from the chipset should work.

Regarding PCIe socket selection, ensure that the PCIe socket
1. uses free PCIe lanes that are not shared with other system components like a graphics card or an M.2-based NVMe card
2. matches the PCIe standards and amount of PCIe lanes needed
    A PCIe 2.0 USB PCIe card can be placed into any PCIe slot: 2.0, 3.0, 4.0
    A PCIe 3.0 USB PCIe card needs at least a PCIe 3.0 socket (or above)
    Critical is the amount of PCIe lanes in a socket; for an x4 card you need at least a PCIe x4 socket (or above)

You can get this kind of information from the manual of your mainboard.

A couple of questions:
- What mainboard do you have? What's the URL to the mainboard manual?
- Which extra USB PCIe card did you buy? Do you know the USB controller?
- Into which PCIe slot of your computer did you place it?

So you still have USB transport errors. Both numbers are counters. In the manual you see a screenshot with "0/0".

The cable from RME could be damaged.
I am not sure whether the combination of a USB-C cable with an adapter is solid enough.

I would get a Lindy quality cable to exclude the possibility of a cable problem.

You mean more error counters? It's surely OS and driver dependent and most likely depends on what checks are available for USB 2 and USB 3 specific transport modes. I can only assume that as I have no driver development skill in that field.

Can be everything up to mainboard design, chipset, influence of graphic card or other drivers

BTW, you didn't deliver any information about
- Mainboard
- Details about BIOS settings that you used
- PCIe USB card and which USB controller
- LatencyMon results
- Maybe wrong energy profile
  In the energy profile maybe energy saving settings for USB and PCIe
- The type of your CPU with Intel Big / Little cores
  Windows 10 has not the latest and greates mechanisms built-in to distribute processes/threads to the proper P-/E-cores
  Workaround could be using Bitsums Process Lasso Pro
- Maybe a BIOS update could help
- Check for heat issues; not that throttling of CPU clock is causing this.

Its really difficult to troubleshoot this from the distance.
Find out the minimum amount of steps on how to reliably trigger / reproduce the issue of CRC errors and audio loss.
You need to be able to trigger the issue (be it CRC errors or audio loss) best in only a few steps and short amount of time.

Then perform a "vanilla" parallel installation of Windows and look whether the issues are still there or gone.

First check without any drivers installed if possible. Only DAW or application for audio playback.

Then install all needed drivers but one by one and re-measure with LatencyMon and check whether the error shows up again.

I would also perform a Macrium Disk image after each of the steps to be able to come back to previous state.

Along this way you can also double check different BIOS settings.
Also watch CPU temperature. CPUID HWMonitor can be useful for looking at that.
I am using gadgets for this.

Could also be issues with nVidia card.
To get rid of audio loss every 10-20 minutes I had to disable energy saving on the nVidia GPU using powermizer utility from a russian developer. But I had no USB transport errors when I had these issues.

Very difficult to say whats the root cause, its kind of detective work.
Best is to start with BIOS tunings (e.g. to turn off C-States) so that the CPU does not perform energy saving.
You might have to enable TURBO but for a test to disable SPEEDSTEP to get a constant CPU clock.
Constant CPU clock is better than changing clock.

You can take a look at my blog article to get some additional information how I installed and fine tuned Windows 10.
You find there LatencyMon measuring as well for comparison.
https://www.tonstudio-forum.de/blog/ent … lts-en-de/