This debate has gone on for too long. I think it's silly. Obviously, some manufacturing plants, such as ATI, would sit idle for long periods of time if they made only ATI products. Instead they contract out their plant to other companies. This is widely done, and not just in the audio electronics industry. Do you believe that all the brands selling HDTVs actually have their own factories?
ATI might make an amplifier (or parts of an amplifier) identical to one of their own designs, and sell it to other companies for further assembly or to sell rebadged. They might make an amplifier for a third party that shares some of their own design and parts, but also has other different design features and parts. Sharing some parts is also a way to save costs. And finally, they might make an amplifier for a third party that is a completely different design requiring different parts.
There is nothing wrong or unethical about any of this. In fact it makes for more economical use of valuable manufacturing facilities. ATI would gain from selling the services of its manufacturing facility as well as the skill and experience of its employees.
