This new edition from the Forellenquintett is an Urtext edition based on the manuscript placed in the archives of the Augustine Monastery of St. Florian in Upper Austria. This manuscript was written by Albert Stadler (1794-1888), a friend of Schubert who was living in Steyr in 1819; same year and place that Schubert finished his quintet. This is the only surviving manuscript from the piece, since the originals from Schubert are lost. The front page of the manuscript indicates that the piece was dedicated to Sylvester Paumgartner, a amateur cellist and music patron living in Steyr. Stadler wrote this manuscript in parts for each instrument and it was presumably written for a performance in Paumgartner’s garden (maybe the première), which strongly suggests that the original manuscript from Schubert was in score format. The first Forellenquintet edition was made by Josef Czerny Musikverlag in Vienna, who bought the original manuscript in 1829, right after Schubert’s death. Since this originals are lost, the first edition have been used as reference for the later editions ever since. By comparing the Stadler’s manuscript with the Czerny edition, we can realize that Stadler, while copying from the originals, made small modifications from the score, and the most notable one is on the Double Bass part (Violone on the manuscript). Stadler never went below a F2 (on Double Bass notation) in the whole piece. This strongly suggests that Stadler has adapted the Double Bass part to the Viennese tuning (a five string instrument tuned A, F#, D, A, F), which was largely used in the classical period in Vienna and probably still played in 1819. 
This may have been overlooked for many years, since the manuscript from Stadler was rarely printed in original, usually used only as research material or as a comparative source to the Vienna’s first edition. Nevertheless, we believe that the Stadler’s manuscript is an inestimable important document and absolutely worthwhile to be printed in Urtext. This might be also a major alternative for the Viennese tuning bassists or to the modern bassists playing with four strings without an extension.