When 0000 0000 0000 0000 changes to 0000 0000 0000 0001, the audible different will be 0.0016479 dB.
Dude, there are not 65,536 bits in a 16 bit sample. There are 16 bits in a 16 bit sample. There are 65,536 possible values that can be represented by a 16 bit number. You are confusing the possible number of sample values with bits.
And what do you mean by "When 0000 0000 0000 0000 changes to 0000 0000 0000 0001"? And what does that have to do with dB's? Do you know the definition of dB? FWIW, it is 20 times the log of the ratio between two numbers. What ratio are you using? If you were taking the ratio of 0000 0000 0000 0000 and 0000 0000 0000 0001, that doesn't make sense. There is no such thing as a log of 0 and if you invert the ratio, you'd be dividing by 0 (also no such thing).
I'm not trying to piss you off or anything, but I'm thinking you don't really understand the concept of a logarithmic scale, what is meant by dB and how those two concepts are related.