As you can see in my video above, there is both video and audio mixing. The video combines in various modes, which are just a button press away. The audio can be switched on and off using three different switches, so you can use a separate microphone if you wish, along with the audio in via HDMI. While I didn't show it in the video, you can either use the mixed analog audio out, or you can use the loop HDMI audio out, or even the OBS audio capture mode via USB 3.1. When it works properly, I've been very pleased with the results. I actually did a separate video review of Fatal Fury: First Contact, and used the j5create JVA06 to do the video and audio mixing (not my voice, but of the games) here:

As you can see, I am able to switch between video and audio sources - in this case, my laptop and Nintendo Switch, with ease. It's just a button and a switch to change each source, and it makes the above comparison video a piece of cake.

From a technical perspective, there is video chroma crush on the OBS captured video, but not on the passthrough video. This is very common and not a major cause for concern. If you would like more information on what this means, please look here:

https://www.rtings.com/tv/learn/chroma-subsampling

There is a small amount of latency between the cloned video and the passthrough video; no more than one frame. Here's a picture to show the delay, taken with my cellphone camera:

This means that you could easily play games using the passthrough video, or use this device for live video situations, where you want to do a presentation with a camcorder on one side and a laptop on the other, or two videos/games/etc. as necessary. For the OBS capture, the latency between the real-time output and the captured video is approximately 3-5 frames, while it captures at 60 frames per second. So that's approximately a 50ms to 84ms delay. Here's a picture I took to show the delay:

While this means that you might not want to play games directly off of the OBS captured stream, thankfully with the passthrough port, that isn't necessary.

The audio mixing is also really useful. While adjusting volume from the device doesn't appear to be supported, it does display the volume level on each source in an easy to see glowing LED, making it a cinch to visually determine if any of your sources need adjustment, and it's also great for sound checks on the input side. You can also use the speaker out for an analog mixer from there, or just use the direct HDMI or OBS capture. Being able to turn on and off each individual audio source just adds to the flexibility.

The only problems I had with the device was that one of my laptops had a problem with EDID detection when connected to the JVA06 by itself, but my other laptop worked perfectly. I'm not sure what the problem was exactly, but it worked great when it did work. The other issue related to what I mentioned before about audio mixing; pay attention to those LEDs, because thanks to them, I noticed that my laptop's HDMI out was much hotter than my Nintendo Switch's, so when I switched between the sources in my Fatal Fury comparison video above, I had to set my laptop's volume to 50% while leaving the Switch at full volume. Once I did that, it worked great, as you can see above.

The j5create JVA06 is such a cool little device. I have to admit that I may not use its extensive feature set too often, and it is pricey to get that feature set, but when I do need it, it'll no doubt bring a smile to my face. Comparing the same game on multiple platforms, for example, will now be a breeze. I guess my only other desire would be to see a version of this device that supports 4K resolutions. Hopefully this is on j5create's future roadmap!