I've not yet studied any works in which I've actually felt the socialist realism that is so often derided in works from that area and time.
Try Prokofiev's WAR & PEACE - a 100% distortion of Tolstoy's novel for Stalinist ends :( The finale is ten solid minutes of authentic soviet realist outpouring ;)
While you are mining Prokofiev's operas for soviet realist content, try POVEST' NASTOYASHEGO CHELOVEKA (aka "Story of a Real Man") - an operatic interpretation of the life of a USSR WW2 fighter pilot who was shot down over no-man's-land, crawled back through the lines, was rescued by partisans, fitted with prosthetic legs, and returned to active service. The final scene shows a Great Leader (who is, of course, Stalin) visiting the pilot in his rehabilitation clinic after the war, giving him a medal and awarding him an apartment of his own.
As I said above, I think it's a mistake to label this music 'bad' or 'wrong' - it was written for different ends, for a society radically different to our own. It (often) achieves those ends very successfully in its own terms, even if we find the result unpalatable or naive by our own different standards.
In point of fact there have been recent attempts to 'rehabilitate' some of these socialist realist works. Helikon Opera here in Moscow created a staging of Story Of A Real Man for the 60th Anniversary of the end of WW2. Although the plot was largely left intact, the final scene was entirely altered - since a contemporary Russian public would not brook the eulogy to Stalin at the end. Instead of a Leader, a German journalist visits the pilot in his squalid hospital, to interview the legendary WW2 "ace" who is forgotten in his own country and dumped in the corner of a ward. The point was not only to find a more 'acceptable' ending, but to make a political point - about the scandalous treatment of Russia's disabled ex-servicemen. I was at the opening night, and there were nearly riots - which were quelled when a war veteran in the audience stood up and said "be quiet, all of you! this is our story, it is about our sacrifice!".
