Born in Den Haag, son of the composer August Seiffert (d.1894)
The Berlin address book lists Seiffert until 1936 as Tonkünstler. The 1937 edition doesn't list any Seiffert at his address Kantstrasse 103 in Charlottenburg, therefore it's unclear, whether he left Berlin or died.
Seiffert married 1919, the marriage certificate contains his birth date. (accessible via ancestry.com)