Using 2 PP's in series?

I currently have a P5 that I’m quite happy with, but, am thinking about purchasing a P15. My thought is this, can I run the P15 as a main PP and plug the P5 in to it for all my source equipment (DS Dac and Memory player as of now, pre amp maybe) and plug my amp in to the P15. Would there be any benefit to running it this way? Any problem?