Has anybody bought or heard a Chinese knock off amplifier?

Short response: if it breaks or comes to you nonfunctional, will you be able to say "Oh well", and throw it away or try to fix it yourself?
Long response:
There are some really good Chinese products, but if you have an issue or your component breaks and you can't speak Chinese, forget it.  If you must buy Chinese, go through a seller in your own country.  A lot of their HIFI components are not particularly cheap, so if it breaks you are left with a paperweight/doorstop.  Even with the name products (not counterfeits) it can be difficult/impossible to get satisfaction.  I've had issues with Topping products in that I was sent a UK plug for US use and spent many weeks just trying to get the Chinese dealer to understand that I needed the US one (Shenzhen Audio didn't give me the option of picking US/UK plug, and Topping usually sends both).  Never resolved - instead of sending me the correct wall wart adapter I needed, they sent me an IEC power cord which was useless for it.  Sent pictures of what I needed, and got back polite, nonsensical responses.  Second was a Topping DAC that had the lettering on the front upside down (same seller) - they offered $20 refund for a $750 unit.  Even with a company like Denafrips, you can't return something just if you don't like it, and any repairs you need (even under warranty) after 30 days you have to pay shipping costs to send it back to them.  The Chinese knockoff guitars of famous brands are nowhere near the quality of the US models but they don't even try to pretend that they're the real deal (and they're a lot cheaper), so you know what you're getting.

Mistrust of China is ridiculous, how often does China send soldiers to invade another country?

You might like to address that question to our friends in India at this very moment.
Or pose that first part to our friends in Hong Kong and Taiwan.
Or Vietnam.
Or Thailand.
Or Cambodia.
Or any country near the South China Sea.

if you look at the way Chinese counterfeits are made and sold you will realise they are not meant to replace the real thing and are also not meant to fool a buyer. These are for people who want to fool other people into thinking they have the real thing

Going to need a second cup of tea before I can even begin to absorb that one...

I've read about these clones of high-end brands from the likes of FM Acoustics etc. from China on another forum 2 or 3 years ago. Apparently someone bought the clones and compared them to the original. It was reported that there is a difference in sound quality between the units but it is not significant and very close.

I don't think anyone here in their right mind will consider buying clones or counterfeit gear from China. Personally I don't buy anything Made in China for my hifi.

Currently listening to a Chinese Icepower amp - 50ASX2SE into Klipsch Forte speakers.  $160 shipped.  Arrived in about 2 weeks.  Very smooth tube-like sounding with nice bass and midrange.  

I paid $20 for a Chinese tube preamp and modded it to a cathode follower circuit.  Sounds great buffering my DAC and phono preamp.  

Was a time when anything made in Japan was considered a joke.  Not anymore and China is following the same path.  I own a Chinese made 5 string banjo which costs $1,000 now.  It holds it own against a 5K American made instrument.  

I would certainly advise caution when purchasing this Chinese stuff but my experience has been good.