There might not be a brand name for the modules, in the traditional sense. I did some poking around on AliExpress, and found similar modules to both of the ones shown in the pictures. I've also played with power amp modules from AliExpress, but ones with a lot lower output ratings, such as 6 Watts per channel for my workshop speakers.
It gets difficult because there are often dozens of vendors for a given module, often supplying copy-pasted data of varying detail. On the other hand, once you find out what power amp chip is being used, you can look up the datasheet for the chip and learn a lot about it. Many of these modules make it look for all the world like they cloned the manufacturer's recommended application circuit. Now, whether they're using genuine parts and building it with quality is something you'd want to take up with the vendor. But it may be unknown who actually makes them.
What's not clear is how an off the shelf module, even an IcePower, becomes a bass amp. If I've learned one thing from Andy over the years, a lot of thought goes into addressing the specific issues that make a portable musical instrument amplifier different than a hi-fi amplifier.
An industrial, high volume customer may be able to track down the original designer and manufacturer, if they want a more robust supply chain. But I don't know how to do that. It may require "boots on the ground" in Shenzen.
