Symmetrisches Konzert (symmetrical concert) created and performed by Gerhard Behles and Robert Henke. Both performers sit on a table, facing each other. Both operate a Yamaha SY-77 FM synthesizer keyboard, one of their favorite instruments: They start with the same sound, a complex FM sound with looping envelopes. They choose sustaining notes by putting matches in between the keys. Over the course of the concert they change the synthesis parameters by typing in new values and thus create a constant morph from the starting structure into something potentially very different. In the last part of the concert they come back to a common state by step by step setting their machines to the same set of parameters. The concert starts with symmetry and it ends with symmetry.Symmetrisches Konzert has been successfully performed in various locations in East-Berlin in the 1990s in front of audiences as big as twenty five people, and once in Lisbon at a festival in front of a lot more quite confused folks.