One does not usually associate Italy in the last century with the Symphony as a musical form. Respighi wrote an early, derivative(albeit sumptuous) Sinfonia Drammatica but towering figures of Italian music like Goffredo Petrassi and Luigi Dallapiccola did not write symphonies. (Petrassi did compose a very fine-if increasingly difficult, I find-series of 8 Concerti for Orchestra).
I invested some years ago in the Marco Polo set of Gian Francesco Mailipiero's eleven numbered symphonies and five other named sinfonias played by the Moscow Symphony Orchestra conducted by the late Antonio de Almeida. These are fascinating compositions, rightly acclaimed by the leading Malipiero expert John Waterhouse. While applauding Marco Polo and de Almeida's enterprise however, I cannot but feel that the performances are not much better than "run-throughs" by the Moscow players. These works need much better performances to reveal their real depth. I would though certainly encourage others to give these symphonies a try! Anyone else know the recordings?
I am also intrigued to hear the single Symphony composed by Ildebrando Pizzetti which, I have read, is a fine work. Alfredo Casella wrote two early symphonies(apparently influenced by Mahler) and a third symphony at the beginning of the Second World War but none of these is currently available-Casella's music is only slowly beginning to be played much again after his very high pre-war reputation was damaged by his associations with Mussolini's Fascist regime.
CPO(again!) did record a couple of symphonies by Franco Alfano-primarily another composers of Italian operas-but I would certainly not rate these as masterpieces.
Many do tend to think of Italy-at least pre the Berio, Nono, Maderna era(of which I am totally incompetent to speak!!)-as a country of opera. It is worth taking some time perhaps to explore those composers who also wrote symphonic music.