I chose this because Magewell products tend to have solid reviews and the company officially supports Linux. My only reservation is that the product and documentation don't lay out the basic gotchas you might run into, so I'll do my best to cover those at the bottom of this review.In general, it does what it says. You can give it up to a 4K signal at 60 Hz and it will pass the signal through to the HDMI loop unaltered, and downsample it over the USB to a maximum of 1080p at 60 Hz.Strangely, the box only says it take up to 30 Hz at 4K, but the online description, my eyes, and my TV all agree that it works at 60 Hz.There seems to be a short delay between the source and the USB output. If I were to estimate, it looks like about a quarter second when it's outputting 1080p60, and I think it may be less at lower settings. I expect this would only be a problem if you're trying to play action games through the USB capture. I don't notice any delay on the loop-through output so I'd suggest playing such games through the loop-through.The headphone jack does work, but I'll caution it is not amplified. If you try to plug headphones without an amplifier in you will have a very hard time hearing it.Technical gotchas:First, be sure you're using a USB 3.0 or higher slot on your PC. The easiest way to tell is a USB 3 slot has a blue plastic insert. If you try to use a USB 2 slot it will actually work, but you'll be limited to lower resolutions and frame rates. I did not see any indications from the device when this was happening.Also note this does NOT strip HDCP, and if it receives an HDCP-encrypted signal, it will just output a black screen. Verify that whatever device you want to capture supports non-HDCP output. Off hand, the PS4, Wii U, and most PCs will work fairly easily. Most other peripherals could pose an issue, so be sure to Google a bit to know if your device will work with this.And a Linux-specific note: As far as I can tell, the official drivers don't do anything, at least on modern kernels. This is a minor deal as the generic V4L drivers seem to work perfectly. I installed the official ones to see if they might allow some more specialized configuration, but they don't even detect the device.