Chinese Class A SS

I don't dispute that some caution is in order. China is an enormous market with a broad spectrum in regard to quality and ethical standards.  My only point is that you can definitely find high quality products made there. To castigate all their manufacturers is erroneous. 
Charles 

Malaysia, Indonesia, India, Bangladesh, Africa, and depending on how the politics go, Cambodia and Myanmar / Burma.

Bando, of Japan..the transformer maker...has been using Indonesia for manufacturing it's main line (ie, bulk of transformers made, in numbers) of transformers, for quite some time now. Open up any Japanese (company) amp from the 70's through the 2010's and you might find a 'Bando' transformer in it.

http://www.bando.com.my/timeline.htm

@freediver - I own a number of the amps you mention. They sound very nice. In fact, I have a cheap 25 watt pure Class A Chinese amp that just spent significant time in my main system and I was truly impressed with its performance when matched with much higher priced gear. As people have said, I’m sure parts quality could be better and the designs may not be original (not necessary illegal - a US patent is good for only 20 years and that’s assuming it was patented to begin with). Try one out, you might be surprised.

I find the charge of stealing a circuit design interesting.

For example, when it comes to tube amplifiers, but a handful of designs exist, with almost all developed between the 1930s and 1950s. Beyond the SET designs from Western Electric and that ilk, with an exception or three, push-pull tube amplifiers use the Dynaco (taken from the guitar industry), Mullard (99% of modern offerings), or Williamson circuit, the latter two offered to inspire creating products in the audio market. Same goes for power supplies.

When a company claims their circuit is proprietary, or its developed some exciting "innovations", it simply means they’ve added / removed / tried a different value part to what’s long existed, and felt it worked or sounded better. Look at the schematic (which no one provides anymore), and it will employ one of the aforementioned classic designs.

I’ll use a recipe as an analogy. A restaurant or home cook may have a recipe for chicken marsala or whatever you care to imagine. Their particular interpretation varies in the inclusion / ratio of ingredients and implementation. Does any rational person challenge or denigrate them for it?