There are some discussion in Chinese from Hong Kong and Taiwan, as well as their taobao store, the feedback has been pretty positive especially given the price to performance ratio. I think they are OEM manufacture so they have good wholesale price. The D7 is only 1000 RMB or ~ $160 USB for 1DD and 6BA, so I decided to take a chance.
Go to their taobao site for some frequency graphs, from the feedback and the graphs, they are mostly going for a neutral and smooth house sound.
https://shop583626459.world.taobao.com