It was not a mellow midsummer. Under their director, James Weeks, the choral group Exaudi thrives at extremes that would kill off weaker lungs, and their date in Aldeburgh Church this year was another astonishing feat of versatility. Motets by Byrd, the long-suffering Catholic at large in Elizabeth I's brave new Anglican world, were hurled out devoid of sentiment, but suffused with raw vitality. No conflict at all, then, with Wolfgang Rihm's desperate, end-of-days Quo me rapis: brief, desolate candles of sound, given a morbid sheen of beauty by Exaudi's exactitude.

But it was the implacable music of Xenakis that kept me up throughout the shortest night of the year. First, the cellist Rohan de Saram coolly despatched the swarm of guttural cries and eldritch shrieks of Kottos - missing something of the fury of the piece in the process, perhaps, but not dropping a stitch. And then came the hail of wordless shrapnel that comprises the Greek composer's ferocious Nuits. There are no words at all in this one (the piece is built out of Sumerian syllables) but the pulse and panache of Exaudi's delivery hit you square in the gut.

You can expect that kind of payoff from a composer as direct as Xenakis. But at Blythburgh Church on Saturday, Guillaume de Machaut's long night of the soul, his 14th-century masterpiece the Messe de Nostre Dame, proved almost as stirring. This is composition before the rulebook was written, and the matchless Ensemble Organum under Marcel Pérès responded with pungently evocative singing that made that most predictable of texts - the Catholic Mass - sound eerily spontaneous.

Perhaps the weekend's only disappointment was Aldeburgh's main man-designate: the pianist Pierre-Laurent Aimard, easing into his duties as the festival's artistic director from 2009. His recital at Snape Maltings also went time-travelling, splicing Kurtág's Játékok with wedges of Bach's The Art of Fugue - a deliberate attempt to help us to absorb Bach's counterpoint by seeding it with a handful of Kurtág's puckish miniatures.

But while I loved the cleansing rigour of Aimard's Játékok (Kurtág played like Bach, if you like) his super-polished, studied and highly deliberate Art of Fugue (Bach played like Kurtág, perhaps) didn't always enthral. Beautifully arresting as some of the juxtapositions were, there was something of the precious hovering over the whole enterprise.

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