From 1979 to 1991, he was répétiteur at the Vienna State Opera and assisted conductors such as Claudio Abbado, Lorin Maazel, Michel Plasson, Leonard Slatkin, Riccardo Muti and James Levine in recordings.
He conducted concerts with the instrumentalists Nelson Freire, Barbara Moser, Itzhak Perlman and the singers Mirella Freni, Renata Scotto, Anna Netrebko, José Carreras and Plácido Domingo.
In his appearances in the US and Canada, Sollak has conducted concerts in New York (David Geffen Hall), Chicago, Milwaukee, Hartford, Cleveland, Pittsburgh and Philadelphia, also with Aga Mikolaj and Jerry Hadley, as well as in Montreal, Toronto and Calgary.
His operatic repertoire includes, among others, Fidelio, Ariadne auf Naxos, L'italiana in Algeri, I Capuleti e i Montecchi, La Bohème, Tosca and Carmen.
[3] Sollak conducted the Münchner Rundfunkorchester for radio recordings with works by Elgar, Stravinsky and Sibelius, an aria disc with Lyuba Kazarnovskaya in Moscow and a live CD with the Four Last Songs by Richard Strauss with Aga Mikolaj and the Győr Philharmonic Orchestra.