Born in Limburg an der Lahn, Philippi studied musicology, journalism as well as general and comparative literature at the Johannes Gutenberg University Mainz from 1985 to 1992.
From 1985 to 1989, she also studied at the Episcopal Institute of Church Music of the Diocese of Mainz, where she graduated in 1989 with the church musician examination C. In 1992, she received her doctorate under Christoph-Hellmut Mahling at the Musicological Institute of the Johannes Gutenberg University Mainz on the subject Antonín Dvořák – The Spectre's Bride (Svatební košile) op.
In 2000, she was awarded the habilitation and the Venia legendi for the subject Musicology at the Department of History of the Johannes Gutenberg University Mainz.
From 2002 to 2018, she was a member of the preparatory working group (2004 to 2018 Editorial Board) of the Neue Dvořák-Gesamtausgabe/New Dvořák Edition (NDE), where she also became a research Fellow in 2006.
From 2005 to 2018, she was a member of the international editorial board (Mezinárodní redakční rada) of the journal Hudební věda published by the Czech Academy of Sciences in Prague.