It may well look a little bland, but it's an excellent 400-watt digital stereo amp, based on the classic Hypex UcD400HG modules. Professionally assembled by DYI Cable.
(One channel is not working, which is very likely a bad UcD400HG module that can be purchased for a total of about $138.00 using the above link. Replacing the module is not a lot of work. Then again, it could be just a fuse. Anybody with basic knowledge of electronics should be able to diagnose and fix.)