The Armida Quartet is holding an unusual kind of rehearsal, skimming through three Mozart string quartets with musicologist and Henle's publishing director Wolf-Dieter Seiffert. The focus this time is not on sound quality, musical character, or developing an extended formal overview- all qualities for which the Armida Quartet is well-known- but on achieving a good match between philological accuracy and practical music-making. Seiffert is working on a new edition of the Mozart string quartets for his publishing house in Munich, and has sought out direct contact with the members of the Berlin string quartet to clarify doubts regarding dynamics, ties and tempi. When a case is truly difficult, the most technically feasible or desirable alternative helps him decide which variant will ultimately figure in the new Urtext edition: will it be a variant from Mozart's autograph, or from the first printed edition? This method is particularly productive when an editor can work with ensembles as well-versed in historical performance practice and aesthetics as the Armida Quartet.