Well, it's largely based on the SR-71A (but may not use the same opamps). The PCB is also not of the same quality as a typical RSA amp, but appears to follow the SR-71A layout quite closely. Clearly, you can't expect an exact clone of an SR-71A at this price!
It is assembled by a semi-DIY operation in Anhui Province, and the general component quality appears to be good (i.e.it doesn't appear to be full of fake components). The enclosure is a generic project box (albeit a good, solid one), and has a few sharp edges. The volume pot is quiet and has good channel balance at low levels.
As for the SQ, it has incredible dynamics and a very deep, extended and powerful bass. It appears to have a high electrical damping factor and matches the T51p (for example) well. It will also drive high-impedance cans and some planars effortlessly.
The downside is a slight veil in the midrange, but this is not a deal-breaker. This may be due to the choice of opamps - who knows...
Apart from the obvious legal / moral issues associated with a product which is clearly based on someone else's work / IP, even if it is not an exact copy, the SQ for the asking price is very good. Be aware, though, that it eats PP3 batteries for breakfast, lunch and dinner.
