Marco, I did try the distributor. He insists that the Cayin 6cg7 is just that. That the 6n6 imprinted by the tube manufacturer is "just a production code". He also sez the difference between them and other 6CG7's is just an issue of high gain which is too much gain in this amp.
With my SED KT88's he is right on (!) and they sounded best with the Cayin '6cg7'. He was willing to sell me a matched pair for $50. I asked for 3 MP - he said he would see if he had that many (?) and would call me back. He never did call back. I'm not too surprised - he may have been suspicious of my 'use' of these tubes. Considering that I had previously told him that he was mis-advertising the power out put of this amp and didn't change his ad after I notified him, I can see why he might disappear. Or perhaps I'm just paranoid. Or perhaps he is. :-)
BTW, should any Cayin A100T amp owner read this and be curious or concerned, I did some tube switching in the amp. I'm using EH 6cg7's and Tung Sol 6550's. The sound is rich, full, retaining good resolution and with out diminishing the highs at all. Nice combo actually. (The Cayin 6cg7 and the Tung Sol combo was poor. The highs were rolled substantially and the remainder lacked resolution.)
I bought a pair of Russian 6N6P's and one day I will have some one compare them to the Chinese 6N6, perhaps aka a Cayin 6CG7, to see what differences actually exist between the 3 differently designated tubes.
Fun ain't it!