Here is my setup
I had the same issue. Running a legacy 5.6 php x64 which needed the interface because of the hard RAM restrictions 32 bits give.
The solution was in the unoffical driver offered by Rob.
https://robsphp.blogspot.nl/2012/06/unofficial-microsoft-sql-server-driver.html
I tested it out, and it works properly with 5.6.33 x64