Koch turned increasingly to concert conducting from 1967 and was succeeded by Karl-Ernst Sasse Head and chief conductor of the Philharmonisches Staatsorchester Halle. Koch "wanted to form an orchestra that should correspond to his high ideas", as journalist Gisela Heine put it. In Halle, he arranges the Handel Festival Halle and the Musiktage with. Thus, on the occasion of the 1970 Handel Festival, he conducted Beethoven's Tripelkonzert, which was interpreted by the Soviet guest musicians, violin virtuoso Oleg Kagan, pianist Elisabeth Leonskaja and cellist Natalia Gutman. At the Wittenberg "Weeks of Contemporary Music" in 1971, he participated with a performance of Leoš Janáček'sSinfonietta. Moreover, he premiered several contemporary musical works by GDR composers, among others in 1969 Heinz Röttgers Violin Concerto (with Gustav Schmahl) and in 1970 Hans Jürgen Wenzel's "Trassensinfonie". Wenzel's work, however, which had not been awarded by the Association of Composers and Musicologists of the GDR [de] (VKM), led to conflict with Koch, whereupon from the 1970s onwards he initially deferred contemporary music and thus in effect sound creations from the region in the programme planning and from 1979 also in Wenzel's progressive Series "Confrontation" of the Halle Philharmonic. In 1972 Koch took over the direction of the Hallesche Philharmonie, which emerged from the former State Symphony Orchestra, the Robert Franz Singing Academy and the Stadtsingechor zu Halle [de]; furthermore, a separate chamber orchestra, which he conducted from 1973 to 1984, and two wind groups were pronounced. According to the musicologist Konstanze Musketa, this resulted in "a versatile and powerful ensemble", from which "essential impulses for the musical life of the region" took their starting point. In 1976, he conducted the festive concert on the occasion of the inauguration of the Konzerthalle St.-Ulrich-Kirche [de], which was to replace the Steintor-Varieté [de] as the main venue. Koch advocated a "democratisation of concert life", which was expressed in introductions to works and talks as well as concert planning. Thus, according to Richter, his Werkhalle and student concerts were an effort to "introduce those circles to classical music." The concerts were considered to be largely sold out. The ensemble's repertoire included symphonic music from the classical period to the modern. The choral-orchestral connection allowed repeated performances of oratorios by George Frideric Handel. For the 450th anniversary of the German Peasants' War, it premiered the oratorio "Die Antwort" by Wolfgang Hohensee with a text by Paul Wiens in the St. Mary's Church, Mühlhausen under Koch's direction. The merit of the symphony orchestra, the chamber orchestra and the chamber music ensembles for contemporary music should also be expressed in further premieres. However, composers from the Halle-Magdeburg area were hardly considered by the Philharmonic. Due to his inactivity, Koch was also not re-elected as chairman of the performers' section (1972-1976) in the corresponding district association of the VKM. On the other hand, Koch "never chose according to affiliation to trends and fashions, but always with regard to their musical quality", as Richter elaborated. Moreover, the "effect of the sonic result" was important to Koch. Among the works presented were Alan Bushs 1972 symphonic movement for piano and orchestra "Africa" (with Alan Bush), 1974 Fritz Geißler's Symphony No. 8, 1975 Günter Kochans Viola Concerto (with Alfred Lipka), 1981 Wolfgang Stendel's Cello Concerto (with Hans-Joachim Scheitzbach) and in 1989 Kurt Schwaens 2nd Piano Concerto (with Ton Nu Nguyet Minh) and Dietrich Boekles new version of the Concerto for large orchestra. Regularly the orchestra was invited to the major alternating In 1989, he performed at the Dresdner Tage der zeitgenössischen Musik [de]. Clearly visible under Koch's conducting was also an international recognition, as Musketa pointed out. Numerous guest performances took the orchestra to the so-called Eastern Bloc. Koch's "authority and negotiating skills", as stated in an obituary in the Mitteldeutsche Zeitung from Halle, also enabled the Philharmonie to make concert tours to the Non-Socialist Economic Area from 1975. According to the musicologist Achim Heidenreich, in addition to these regular events in the Federal Republic of Germany, which were quite positively noted, German Communist Party organised workers' concerts were also served, which, on the other hand, were not very well received. The dramaturge Gerd Richter perceived Koch in Halle "as an imaginative, outstanding artist and clever manager". He found impressive "his high musicality and his elegant, yet also precise, percussion technique, his ability to accurately assess the effect of a piece of music when reading the score, but also to be able to convey this to the performers as well as ultimately to the audience". Koch had a "tendency towards a certain theatricality", according to Richter, and possessed a "strong, at times egocentric, personality". Despite not having studied at a conservatoire, he was "open to all artistic and intellectual stimuli, indeed he had a pronounced thirst for knowledge" and was also concerned, for example, with the maxims of historical performance practice.