Drop in tube replacement 6N6 v 6CG7

I have a Cayin A100T amp. It uses "6cg7"s as drivers. I dropped in some EH and some EI 6cg7's and for the first time noted that these tubes did not look like the "Cayin 6cg7's. The Cayin bottle was somewhat larger and the plates were somewhat smaller, about 30%.

Close inspection of the Cayin tube showed faint manufacturer logo, a Chinese firm, and the tube identification number 6N6.

The questions that concern me is 1)Was the Cayin designed with a different tube than the one advertised? 2)Did the manufacturer's gremlins just stuff in the wrong tubes b y accident? 3) Is there any chance that the 6n6 is a drop in for a 6CG7?

Sonically the EI and the EH tubes are more robust, the Chinese tube more laid back and, I think, less resolving, but so far the amp has not died because I've used them.

Thoughts anyone?

PS NO help from the dealer, or the distributor, so far and I wish I could say that this is the first problem that they have ignored.
Hey Newbee - one of my favorite sleeper preamps, the Cary Slp-50A used 6CG7's. I owned one for many years. I have a butt-load if you want to procure some good ones (even after that descriptor) to experiment with. I no longer have the Cary (great little pre for the money) so can only use them in my Modwright Transporter and there are better options there.

As far as 6n6 - a Googlization provides much input on the subject.
Marco, Thanks for the offer. Problem is I think that a regular 6cg7 has too much gain for my A100T Cayin when using KT88's. I guess there are other tubes and combinations possible, but I'd at least like to resolve this 6N6 issue. I checked the google page and I couldn't find a definitive answer. Lots of talk though.
I'm afraid I don't know squat about 6N6's, Chuck. Wish I could be of more help. Did you try the distributor?
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!