Douk Audio. Any experience with any of their products?


I've seen several products under this name on eBay in recent history, including a tube preamp board that looks pretty impressive. Especially for the money.   They reference a pretty exotic Audionote preamp in the title.  

Douk Kondo Audionote

I noticed the url on the board, and decided to find out more. Turns out the entire website is blank. Assuming this was an error, I messaged the seller.

"Hi,
I was interested in learning more about the Kondo board, and tried the website to see what info was there, and I get a blank page. Just fyi."

I thought they might appreciate the heads up about the error. Instead, I received this response:
 
"Hi dear customer
wish you have a nice day
the amp board designed by our designers
so you cant find it
best regards
Douk-Amy :)"


Not exactly a confidence builder. I'd be interested to hear if anyone has had direct experience with these folks.
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Like kotta, I just bought a Dun Mei Av21 buffer pre amp and put nos 12au7 tubes in it.  

It makes jazz sound less digital and smoother but I do have an audible hum from the power supply.  Is this normal? 
doukmall is  a pretty reputable seller. Have bought 3 things from him including a pHono preamp with a ground hum issue. They took it back and issued credit. other items worked as advertised.

The last few years, the Chinese have really upped their game. Quality is much better, no more cold solder joints.

and the latest tubess from PSVANE Gray glass are reallly really good.

J
Douk did not strike a good chord with me. I ordered a pre amp kit, board with some sockets and heat sinks, 24 dollars total. Not too bad, the board was good. The trouble begins when I am looking for a schematic or parts list. Their response was that the schematic is encrypted. The parts list is the circuit board. I have been making these type of kits for over 30 years. Even the basic kit gives you a shopping list of capacitance, resistance, voltage ratings, tolerances of these and so on. If I cannot decipher your board, don't insinuate that I am unqualified. I have been a tech for 30 years now. I have been unable to find out any more info on this preamp on the web.
I am interested in the Douk Audio “MC” (moving coil) passive preamp, however I’m not sure I understand what the term “passive” means in this case; does that mean zero gain? A previous post seemed to hint at that definition of “passive”. If so, why would I buy a zero-gain preamp for a MC cartridge when what I need is amplification to yield enough voltage to drive a MM input on my preamp? That’s not amplification at all.

Or am I just really misunderstanding something here?

Thanks for any info anyone can provide.
It's passive since it uses transformers, rather than active electronics.  This one is pretty cheap for what it is.  The alternative is an active MC head amp.  These can get quite expensive.