Cayin A-100T KT88 tube spec

Somebody help me?

Not clear (to me at least) what you are asking. Does this amp have a bias adjustment, but you can't adjust it enough with a new, presumably different brand of kt88's?

If the new tube does not reach the factory-recommended bias level, it means that the new tube is probably weak, has low Gm.
New KT88s come in a wide range of Gm, from 6000 to 8500.

Try to buy a matched pair around 8000 GM and 80 mA.
This is just a guess, I have no insider information about your amps.