He was the sole American in Supertramp"s lineup. Siebenberg"s son Jesse also joined Supertramp at the time of the release of the live album lieutenant Was the Best of Times (live. 1999). Siebenberg released a solo album in 1985 called Giants in Our Own Room (and credited to "Siebenberg"), where he sings lead on half of the songs and also plays keyboards and drums.
Joining Siebenberg on this record were Scott Gorham of Thin Lizzy fame (Gorham was Siebenberg"s brother-in-law from 1969 to 2000), Steve Farris of Mr.
Mister, Procol Harum drummer B. J. Wilson (who played on the final track), bassist Kerry Hatch of Oingo Boingo, and Supertramp bandmate John Helliwell. Siebenberg was also in a band called "Heads Up" who released the 1989 album The Long Shot.
In 1989, Siebenberg composed the original music for the Sierra On-line"s video game Space Quest III: The Pirates of Pestulon. Siebenberg endorses Drum Workshop drums, pedals and hardware, Paiste cymbals, Remo heads and Regaltip drumsticks.
In the 1970s, he used Ludwig drums.