Prom 15: Die Walküre, Staatskapelle Berlin, Barenboim

Things may be falling apart, a storm now rages but new broods of humans and demigoddesses have been fathered by chief god Wotan, who has undergone a Doctor Who like transformation from Iain Paterson into Bryn Terfel.

Four new top singers appear on the scene after Monday night’s Rheingold superhumans, but Daniel Barenboim is still very much in control to colour and shape another deluxe semi-staged narrative in his Ring epic, this time about the steely warrior-maiden Valkyrie who came to know love.

You’d expect Nina Stemme, many people’s favourite Wagnerian soprano, to dominate the picture as Brünnhilde along with Terfel's riven father Wotan. But the elongated tragedy of Die Walküre, the most perfectly self-contained of the four Ring operas, only brings the tetralogy’s redemptive heroine into focus after setting up a lesson in love that’s doomed to fail. So for what is perhaps Wagner’s only Ring act that can be performed successfully by itself, we need two sibling lovers of colossal soul, voice and stamina. Simon O’Neill has the latter two qualities as luckless Siegmund; the Sieglinde of Anja Kampe (pictured below), living all three aspects as if her life depended upon it, is the real star of the evening.

O’Neill certainly surprises: what sounds at first like an underweighted, bright tenor voice, more a Loge than a hero, has stops to pull out – first in the thrilling, string-tremolo backed invocation of father Wälse (none other than Wotan), later in rejecting Brünnhilde’s annunciation that he must die at the hands of Hunding, his sister-lover’s betrayed husband, and leave Sieglinde behind on reception into Valhalla. He's infallibly secure, but his acting is gestural (O'Neill pictured below), while Kampe lights up the stage from Sieglinde's first anxious appearance. Her narratives are anchored by wonderful colours in the mid range, while the top – which once faltered in another still-great performance alongside Terfel, in the Zurich Opera Flying Dutchman back in December – holds firm for the biggest adrenalin burst of the evening, her apostrophe to Brünnhilde as woman-hero, saviour of the child she’s carrying within her.

Comparisons between Wagnerian divas may be invidious, but here are two types: the one (Kampe) who can't help giving her all and may sacrifice her career sooner rather than later, and the other (Stemme), rock-solid in both the depths and the heights of the range, who wisely marshals her resources. Stemme’s is a narrower sound with a faster vibrato and marginally less distinct words, but she can do everything: the terrifying "Hojotohos" of Brünnhilde’s Angela Brazil girl entrance, the solemnity of the Death-Annunciation to Siegmund, the tenderness of the daughter daring all for love. Her first scene with Terfel is dominated, of course, by Wotan’s mighty narrative, where the great bass-baritone starts by following Barenboim’s way of drawing the whole Albert Hall in to catch a whisper but still lacks the last degree of titanic world-weariness – truth to tell, he always has – as the compromised god longs only for the end.

And the end of Walküre is, of course, the great scene between father and daughter, which for me was less moving than usual. Whose stamina was most taxed by the heat: brow-mopping Terfel's, Stemme's – she can hardly be blamed for forgetting a couple of lines – Barenboim's or mine? At any rate the turning-points in the rhetoric did not quite have the customary earthshattering impact, even if as assisted by Justin Way’s discreet direction the personenregie, the interaction of two people on stage was as fine as I’ve ever seen it in the Ring. The LED screen came in useful again for the flames surrounding the rock on which the sleeping Brünnhilde is laid.

Perhaps the failure of the last act to elicit the tears which poured out of me at the end of the previous "curtains" was also due to the bumps that one started to notice in Barenboim’s detail-studded reading. He has never been the most natural master of late-romantic rubato, though as in Rheingold his strings swelled like no others in all the love phrases, woodwind projected aching pathos for both Sieglinde and Brünnhilde and the brass – bass trumpet especially – were as amazing at ringing out into the vasts of the South Ken colosseum as they had been the night before. What a gorgeous vision they all made as scenery behind the singers on the Albert Hall platform, six harps included (DJs could surely have been removed in the heat, though). And the turbo-charged climaxes all made their mark, with clarity and space in the Ride of the Valkyries backed by a slightly uneven line up of Wagnerian ladies (pictured above).

We were delighted to welcome back from the previous evening the stylish-human Fricka of glamorous Ekaterina Gubanova and riveting bass Eric Halfvarson, now transformed from giant into another ferocious upholder of loveless family values. Next stop, the trickiest assignment of all – finding a Siegfried worthy of the name. I shall be swapping Wagner for Britten in Norfolk, but there’s always the ever- and anytime-accessible Radio 3 for consolation.

• The Proms Ring continues on Friday with Siegfried; seats sold out, queue early for Arena and Gallery places
• Listen again to this performance for the next six days on the BBC Radio 3 iPlayer
• Read theartsdesk's coverage of the Proms
• More about Anja Kampe's Glyndebourne Isolde on David Nice's blog