I do not have any personal experience with the Gigaport.
The reviews on Thomann though are very positive, some mentioning the complete lack of noise on the outputs.
There is one review that mentions how the Gigaport had varying amount of noise depending on the USB host device and how he managed to remove the noise entirely using a USB Isolator.
Luckily, those have come down in price drastically over the years with the release of a new USB Isolator chip made by TI. Some examples:
https://aliexpress.com/item/1005001927948863.html
https://www.amazon.com/Topping-Isolator-Compatible-PCM32bit-withstands
https://hifimediy.com/product/hifime-high-speed-usb-isolator-v2/
So even with an additional Isolator you'd be well below half of the cost of a DM7.
Edit: that being said, while the Gigaport is USB 2.0 compatible, it is a native USB 3.1 device.
I do not know if and how the functionality would be affected when run at 2.0 speeds via one of these isolators.
In theory, eight uncompressed 24/192 streams are still less than 10% of the bandwidth of USB 2.0