When digital audio is played  the DA converter has to interpolate between the samples. So if your mix is right at the top, it might happen that  the DA has to go over the maximum to regenerate the analog signal. The graphic below shows what happens in this case.

As you can see, it is always a good idea to leave enough headroom in your mix to let your sound breathe. The pro version of PG-AMM comes with a high precision True Peak detector. You should also use a good True Peak limiter at the end of your master chain.