Addressing the recepient on the cover letter for a PhD application I am applying for a PhD position, and I am required to attach a cover letter with the application.
In the advertisement for the position, the main contact person is the "Head of the PhD program", so it feels natural to address the letter to him.

My question: As this person is also an Associate Professor of Mathematics, which title should I use when stating his address information?

My first intuition was to write:


  Name Surname, Head of PhD program
  
  (other address information)


but this might be a bit unfortunate as he is also an associate professor, which could be considered to be a title of greater value.

Alternatively I could just write:


  Name Surname, Associate Professor of Mathematics
  
  (other address information)


but then it sort of misses the point of why I am addressing the letter to him (though this might be obvious to someone working at their department).

I could also add both:


  Name Surname
  
  Associate Professor of Mathematics and Head of PhD program
  
  (other address information)


Is there a standard way?

The university has their own online system for applying, so this might not be all too important. Nevertheless, I want to make sure everything is right.
In most places any of those would be fine. Some places are very formal about titles, though, such as Germany. But if his were the case here, I think you'd already know that. The important thing is that it get to the right person. It is relevant to the entire committee, of course, not just the "main contact". 

But something simple is fine.