The boards were used - second hand stuff. Correspondence with seller was pleasant but used stuff isn't what I have expected.
I am sorry that I gave neutral rating and inaccurate information: actually, the board is brand new and, even more importantly: it is tested. This indicates that you can buy this product with confidence because testing indicates that the board is fully functional. This seller and this product deserve five stars. When I have received the package I have noticed traces of thermal paste on transistors. Therefore I gave neutral rating, just because the seller was great. Later on I have realized that the board was just tested on heat sink and for proper testing it was necessary to use thermal paste. Also, only power supply connection and output connections were soldered but output connections were not soldered. Clearly, to test the board you need to connect just power supply and load (important). This is clear indication that the board was just tested and it is brand new, and more importantly, now I know, the sound is of the best quality.