Which external USB Soundcard do I need?

where I got my info was experience and hearing this same issue crop up on numerous forums but will leave it with the OP to decide if they want to use a duct tape solution.

Well, Asio4All will work with almost any audio interface as a driver, that is its whole point and also why I refer to it as a duct tape solution because it is a patch of a solution. It "can" work in some cases but can also be a cause of much frustration due to how it works and the purpose of why Asio is even needed in the first place. Issue I find is most people have no idea what ASIO is or why it is even needed over the windows shared drivers. Everything works until the point where it doesn't.

There is a reason I know of, and suggested against using the cheap Behringer devices that do not offer a dedicated ASIO driver. If you need some depth as to my experience, other than actually using Asio4All for years in the early 2000s, I have seen it discussed for at least a decade or more on numerous forums including this one and Abletons forum and also doing support for a company BaseHead Inc for 3 years working through hundreds of cases where using Asio4All was the cause of countless issues like this, i'd say i've had enough experience to know when not to suggest it.

To explain the issue:
Windows Audio is a general purpose layer to handle audio input/output for general purpose. It has a lot of features to rout windows audio between applications, through different outputs and to also allow sharing of the hardware between multiple applications at the same time. For playback of typical audio from a simple stream or video games this is usually no problem.

The issue that will arise when you try and demand the system actually generate audio from synthesis, process via effects and then output via the audio interface is some time is needed to do all that maths and generate a sound and the windows audio sub system is not at all designed to handle this kind of demand. Simple sample playback will be fine but synth generation usually results in bad crackles and dropouts where to make it any better you have to increase the buffer which increases the delay significantly.

ASIO was developed to bypass all that overhead and allow a simple 1:1 connection from the software to the interface with the drivers knowing exactly what the hardware can do and allowing a much more robust pipeline. The tradeoff is that only a single application can access the interface at a time. There are now some interfaces that allow multiple ASIO connections but for the sake of this argument, that is not what we are after.

ASIO4All is used to bypass the audio stream of windows and connect to the audio interface just like official ASIO drivers do but it has to put the windows connection off to do this meaning usually no windows audio is available when an ASIO application is in use, the issue the OP already has. Most pro interfaces that have ASIO drivers also offer a second shared audio layer with Windows that allow both windows and ASIO signals to be combined as long as the sample rate and bit depth all match.

Now granted I have used ASIO in many years but it is still considered by most to be a workaround (duct tape) solution to using actual ASIO compatible interface and there's always exceptions to any case but i've learned through a lot of years experience to try and select the best solution to a problem, not the cheapest.

If there is anything insightful you could add that confirms it will work as required, more than happy to learn, it's basically how i've come to know the pitfalls of using A4A so far.

well if it works and you are confident it fits the requirements that’s fine.

Check your windows audio settings. It sounds to me that it's not configured to use the Audio 1 as output.

In windows device manager it should be possible to disable the PC's onboard audio device driver and hopefully force the audio to only use sound output from the NI Komplete Audio 1 interface. Try this and see if that makes any difference. Sounds to me like there's a conflict between the 2 audio drivers going on somewhere. If it doesn't work then just re enable the audio driver in device manager.