Katharine McPhee Shares Rocking Video of 3-Year-Old Son Rennie Drumming Onstage – E! Online

Katharine McPhee‘s son is drumming up to the next level. 

After all, 3-year-old Rennie—whom the Smash alum shares with husband David Foster—just made his onstage debut during the couple’s An Intimate Evening with David Foster and Katharine McPhee tour in Washington D.C Feb. 25. 

“Had a VERY special guest join us on stage for the first time,” Katharine wrote in a

. “#ProudMom.”

And while Rennie has some prodigy-level musical talent, which his parents have shown off…