Douk Audio. Any experience with any of their products?

I found some images of the Dartzeel amp.  Looks amazing, but I don't think there is any connection with the audio kits and components sold on ebay under the Douk name.   

Any experence with their passive pre?

I got the "6j1 Valve tube pre-amp preamplifier bass on music fidelity X10-D"
the ad exactly. For $13 bucks. It was an easy kit to build, tiny but I have to admit it held up.
I first put it in between a emotiva DAC and threadhold stasis amp. First my Maggie’s, wasn’t impressed. Laughed cause $12 I’m glad it made sound. But.. it started to warm up and sure I can hear that tube sound. Hooked up a pair of speakers with ribbons. It continued to open up. 
My preamp is a audible illusions modulus 1 tube and This little plastic pretty blue light toy sounded pretty good. damn well worth the $13 I spent. Perhaps,
Improving the cheap components like caps and resistors would make a serious difference. Tubes of course would make a serious deference.
The little engine that could. It's a fun hobby. 

Any particular tubes work with this size tube? These are smaller them 

Jaynewt- which seller did you buy your Dartzeel clone from? Prices are from 800 shipped to maybe $1600 shipped

thank you!!

@jaynewt I'd be interested to know too. Douk sell for $1600ish, but others sell for around 1/2 that. Are they the same clones?