Since he formed his first orchestra, Miguel Caló always kept a very high level of musical quality and of professional capacity when choosing his musicians. Some of them were Orlando Goñi, Carlos Campanone, Domingo Varela Conte, Luis Brighenti, Domingo Cuestas, Alfredo Sciarreta, Raúl Kaplún, Osvaldo Pugliese, Miguel Nijensohn, Pedro H. Pandolfi, Hugo Gutierrez, Hamlet Calise, Calixto Sallago, Orestes Zungri, Américo Cagiano, Salvador Caló, Pedro Sapochnik, Francisco De Lorenzo and León Lípesker. In 1937, Argentino Galván was in charge of the instrumental arrangements, and the orchestra had an exceptional year. One of the most important interpretative innovations he impelled was “violinistic virtuosity”. Up to that moment, tango violins had been limited to “singing” the melodies, and the most representative exponents of this technique had been Agesilao Ferrazzano, Cayetano Puglisi, Julio De Caro, Manlio Francia and Elvino Vardaro. Howevwe, Argentino Galván used the talent of Raúl Kaplún, first violin of the orchestra, writing for him exceptionally difficult passages which required of all the interpretative abilities the violinist had. That revolutionary and virtuous way of playing the violin would reach its highest level with the prodigious technicality of Enrique Mario Francini and, later on, with Simón Bajour, Reynaldo Nichele and Fernando Suárez Paz. By 1940, Miguel Caló integrated to his orchestra a group of young musicians who turned the orchestra into a central exponent of what was known as “the 40s generation”. All of them, without exception, would become the best musicians of their generation, if not of the whole tango panorama, without chronological distinctions. That group Caló had created was formed by Héctor Stamponi, and then Osmar Maderna, in piano; Domingo Federico, Julio Ahumada, Antonio Ríos, Felipe Ricciardi, José Cambareri, Armando Pontier, Carlos Lázzari and Eduardo Rivira, who used to change places, in bandoneon; Enrique Mario Francini, Aquiles H. Aguilar, Angel Bodas, Haroldo A. Gessaghi y Mario Lalli, in violin; and Ariel Pedernera in contrabass. The influence of pianist Osmar Maderna was prominent in the orchestra’s structure. Maderna also was in charge of the instrumental arrangements, replacing Argentino Galván and Miguel Nijensohn in the job.