Hainl progressed so fast on the cello and worked so hard that he was soon able to join the orchestra of the Grand-Théâtre de Lyon.
However, wishing to complete his studies he entered the Paris Conservatoire, and won a first prize in the 1830 competition.
He undertook tours to France and Belgium; passing through Lyon he was offered a permanent post.
He in due course became a member of the Lyon Académie des Sciences, belles-lettres et arts, before being called on in 1863 to succeed Dietsch at the Paris Opera.
At the Conservatoire concerts, alongside the repertoire of the time, he introduced music such as the Salve regina by Lassus, excerpts from Armide by Lully, Psalms 42 and 98 by Mendelssohn, piano concertos by Beethoven, Rubinstein and Saint-Saëns (with the composer the soloist in the latter), Schumann's Spring Symphony and Manfred overture, choruses from Wagner operas and violin concertos by Garcin and Joncières (played by Jules Danbé).