Pyramid Analytics can consume PowerPivot Data.
It can happen with several options:
1. Directly from the XLS file : ex: http://spstst01/PowerPivot%20Gallery/pyramidtest.xlsx Syntax= http://{ServerName/DocumantLibrary/FileName.XLSX)
2. Connect to the SSAS PowerPivot instance.
Both of the option works great.
Choose one and start today!
Enjoy it!