This is a recording of a hypothetical. What if Leonard Bernstein had rewritten his opera A Quiet Place for a third time: streamlining the plot, slashing the orchestra and severing almost all musical links to his earlier opera Trouble in Tahiti, to which A Quiet Place had originally served as a sequel before swallowing it whole in the final, 1986 version?

Then he might have created something like this chamber version, commissioned by Kent Nagano from the composer Garth Sunderland. Sunderland has radically reworked the score, discarding some sections, reinstating material that Bernstein cut and reassigning entire arias from one character to another. It’s skilfully done; but whether the result is still A Quiet Place is another question. That it’s endorsed by the Leonard Bernstein Office is irrelevant here: this remains a version that Bernstein never authorised or even heard.

If that doesn’t bother you, read on, because on its own terms it’s impressive. The story – in which, 30 years after Trouble in Tahiti, Dinah dies in a car crash and her husband Sam and dysfunctional adult children Dede and Junior gather to confront their loss – is one of the most psychologically complex that Bernstein ever attempted. It’s closer to John Updike than West Side Story, and although you’d never mistake this recording for a theatrical performance (the conversational exchanges by mourners in Act 1 sound stiff, and a piece of breaking crockery detonates like a hand grenade), the four central cast members are entirely inside their characters.

Lucas Meachem as Sam is the opera’s heart; a performance of intense conviction that takes him from clenched, inarticulate fury to redemptive radiance. As Dede, Claudia Boyle is his polar opposite: bright and clear but capable of floating over even the busiest ensembles. Indeed, the vocal gymnastics of Stephen Wadsworth’s libretto present no problems to any of the cast or chorus, whether Joseph Kaiser’s warm-centred François or Gordon Bintner’s volatile (but never less than musical) Junior.

And in truth, in some of the big set pieces (such as Sam’s explosive Act 1 monologue, in which Meachem colours his lines almost by the word), as well as the numerous quickfire ensembles, it’s possible that the slimline scoring (Bernstein asked for at least 72 players; Sunderland uses 18) might offer a musical advantage. Nagano paces it tautly and his Montreal forces play with sensitivity and style, plus an unmistakable relish for the moments when Bernstein eases into a slow waltz or a tiny hint of Gershwin or Stravinsky flashes across the score.

This was clearly a labour of love, and if it’s a question of a slimmed-down, reworked A Quiet Place in opera houses or (as is currently likely) no A Quiet Place at all, I wish it success. Record collectors don’t face the same choice, and you might feel that Bernstein without the extravagance, the awkwardness – Bernstein without its heart on its sleeve – isn’t really Bernstein at all. If that’s the case you’ll be interested, like me, to hear this for the individual performances. But the composer’s own flawed yet deeply romantic DG recording (10/87) will continue to be your first choice.