Thomas Christian is founder and first violinist of the "Vienna String Quintet". This quintet, established 1986, extensively tours the world, giving concerts in Europe, Japan and South America. Their programmes are well documented on numerous CDs including the complete Mozart string quintets as well as the Bruckner quintet. Besides these pieces with two violas their repertoire includes also the Schubert quintet with two violoncelli and works by Dvorak, Lanner and Strauß with double bass.

Since 2003 Thomas Christian has constantly altered and extended the ensemble in order to be able to perform chamber music for various instruments on the highest level. Under the name "Thomas Christian Ensemble" chamber music works ranging from string trios to great ensembles with winds and strings are brought to the stage. The repertoire consists especially of seldom played pieces like the string quartets of H.W.Ernst, J.Marx or W.Kienzl, but includes also adaptations for chamber ensemble from A.Schönberg and his circle e.g. A.Bruckner's symphony No.7 and G.Mahler's symphony No.4.

The musicians of the ensemble consist of high profile players from the international music scene. Regularly they perform at renowned festivals as for example Schloss Elmau, the Brucknerfest Linz, the Beethovenfest Bonn, at Osterklang Wien and at the Romanesque Nights Cololgne.