I doubt that this line works as expected.
I might agree for the pull-ups but definitely not for the device address. As you try to access two chips with different addresses what makes you think that success with one chip implies the same for the other chip?
The comment on this line is wrong here, it probably should be located one line before explaining the address. As you failed to provide a link to the schematics of the board you're using we must assume you know the schematics and did the address calculation correctly.
As the MAX5816 expects 3 bytes for a standard protocol write operation you code cannot result in any defined reaction of the chip.
If you check the result code of the Wire.endTransmission() call I'm sure you get an error.