Actually, the best way to come nearer to Soviet music is first and foremost to take the works as what they actually are, and that's music.
Oh, I agree with you! And I am often involved in performances of this repertoire here in Moscow :) Our orchestra* has been active in performing 'socialist realist' pieces by Schedrin, Muradeli and others who've fallen out of fashion in today's Russia. Even so, I would stick to my point that the ethos under which this music was created cannot be entirely divorced from the historical circumstances of its composition. For example, we gave the first post-soviet-era performances of Schedrin's opera "Not Love Alone" ("Ne Tol'ko Liubov") a few years ago, for Schedrin's anniversary. It's impossible to stage a work like that without reference to its historic background - the story of a female Collective Farm director, who falls in love with a capable but unruly farm worker who will not obey the rules, and thus she has to fire him. More pertinently, I was engaged as the stage director for a project to stage Muradeli's THE GREAT FRIENDSHIP - contrary to rumour, the entire score and materials are still in the archives, although it's never been performed. However, the Ministry of Culture torpedoed the idea, and Muradeli's masterpiece remains on dusty shelves - for entirely political reasons.
Your point about dividing-off the Stalin period (up to 1953) from the later soviet era is well made. Although the USSR lapsed into economic torpor once again under Brezhnev, the ferocity with which censorship and artistic control were applied in that period can't be compared with the Stalinist era - I suspect, perhaps, because nobody cared so much any longer?
I look forward to enjoying some more of the items from your enviable collection in uploads here :)
*
Actually I do work for two symphony orchestras and one chamber orchestra - it's the chamber orchestra I mean here