From 1969 to 1974, before he had graduated, Plakidis held the post of musical director for the Latvian National Theatre.
In 1969 he received a diploma at the All-Union Young Composers' Competition, for his composition "Music for Piano, String Orchestra and Timpani" and in 1982 was awarded the title of Honoured Artist.
[1] Plakidis's music is often part of the Latvian National Symphony Orchestra's repertoire,[2] and he was commissioned to write orchestral works for their 60th, 65th and 70th anniversaries.
The New York Times described the piano part as "couched in brash, clustered harmonies" and the piece as "fascinating".
[5] Reviews include a description of "Music for Piano, String Orchestra and Timpani" as a "Bartók inspired (...) vehicle for nationalist and separatist feeling".