Two giants of American minimalism bestrode the Thames on consecutive nights last week. Philip Glass’s Akhnaten (1984), the last of his trilogy of “portrait” operas, returned to English National Opera in Phelim McDermott’s preposterously gorgeous, must-see production, new in 2016. Across the river, Steve Reich’s epic Music for 18 Musicians (1976), attracted a capacity audience to the Royal Festival Hall.

Over half a century since its origins in New York in the 1960s (the story is more complicated, but that’s for the lecture room), minimalist music still provokes a lingering fury from those who resist its aesthetic of repetition. The rest of us can unite, quite cheerfully, a fascination with phasing (patterns united and dividing at steady but different pulses) with a taste for the goal-oriented music of Beethoven and Wagner or, at the other extreme, the complexities of Boulez, who refused to do anything twice.

Akhnaten looks, on paper, quite exciting: an Egyptian pharaoh builds a city in praise of his new, monotheistic religion, only to face murder and a return to the old order. In practice, in ENO’s staging, no violent death is more poised or balletic than Akhnaten’s, no insurrection more sensuously attenuated. This is opera of contemplation, ritual and slow spectacle. McDermott and his theatre group Improbable embrace it wholeheartedly. The production, with sets designed by Tom Pye, sumptuous costumes by Kevin Pollard and lighting by Bruno Poet, moves precisely in motion with the shifting, minutely detailed changes in the music. Jugglers, used to ingenious effect, intermittently add speed and tension.

Anthony Roth Costanzo, light in body and voice, graceful and tenuous, reprises the title role, appropriately dazzling in his Act 2 hymn to the sun. Rebecca Bottone, returning as Queen Tye, and ENO Harewood artist Katie Stevenson as Nefertiti head the brave supporting ensemble. No one seems troubled by singing in Egyptian, Hebrew and English. How many extra hours are required, by all, to memorise it is anyone’s guess. The American Glass specialist Karen Kamensek conducted a tireless cast, chorus and orchestra (without violins, their high lines evoked by a synthesiser) in a performance entrancing in all respects.

It’s easy to supply dry facts about Reich’s Music for 18 Musicians: around 55 minutes long; based on a cycle of 11 chords; two kinds of basic rhythm, made percussively or via human breath; includes four women’s voices in the ensemble. Reich (b1936) has provided his own analysis, so you can follow each and every contour and triangulation point. Listening to it live in concert is a wholly different experience, as liberating as abandoning a map and stepping outside into the wilds.

Members of the London Sinfonietta and Synergy Vocals, superbly accomplished, played without a conductor – as Reich instructs – taking cues from one another and keeping the steady pulse going, one player taking over maracas or marimba in perfect relay, as if jumping on a ski lift. Collaboration and intimate teamwork are of the essence. The audience rose to their feet as one in admiration. No Reich concert is complete without Clapping Music (1972) – two people, four hands – expertly performed with only a tiny, split-second glitch. Runner for Large Ensemble (2016), premiered as a ballet at the Royal Opera House, gave a taste of recent Reich, drawing on a bell pattern from Ghana and creating a breathless, serene and buoyant energy.

Two other, contrasting concerts left an impression: the composer Colin Matthews programmed the strings of Britten Sinfonia, together with star oboist Nicholas Daniel, in a Wigmore Hall programme of Mozart, Scriabin, Britten, Richard Strauss, some in Matthews’s own arrangements. The centrepiece was the world premiere of Postludes, an octet in memory of Matthews’s close friend and colleague, the composer Oliver Knussen. Beautiful but muscular, it opens with drone-like attack, full of whirring and liquid string effects, then shifts down a gear late on, when cor anglais replaces oboe in touching elegy.

At the Barbican, the London Symphony Orchestra, cellos aside, abandoned their chairs and stood for Schumann and John Eliot Gardiner, to exhilarating effect. I heard the second of two concerts, featuring (in addition to a terrific account of Beethoven’s First Piano Concerto with Piotr Anderszewski as soloist) the Manfred overture and “Spring” Symphony No 1. That season may not yet have arrived, but this urgent, bristling performance nearly convinced you otherwise. Given the desperation in Schumann’s life, the joy his music sparks is all the more acute.

• Akhnaten is in rep at the Coliseum, London, until 7 March