A few days ago I was punched in the back by a fellow concert-goer. It was the closing weekend of the Edinburgh festival and collective over-saturation was beginning to show its ugly side. The woman behind me was apparently so put out by my crossing/recrossing of legs that she succumbed to the urge to get violent.

Roll on the Lammermuir Festival. For any East Coasters needing a bit of breathing space after the long pandemonium of August, this picturesque and quietly very classy mid-September festival is just the ticket. My favourite thing is to bring a bike and meander between concerts in North Berwick, Dunbar and Haddington, between the secluded kirks at Dirleton, Oldhamstocks and Whitekirk and the genteel estate grounds of Lennoxlove and Gilmerton. In my mind it’s always an Indian Summer during Lammermuir. The brambles are ripe and the chanterelle are in bloom.

Musically the Lammermuir Festival is as subtly gorgeous as the East Lothian landscape. It isn’t a programme built around glitzy names or headline acts but the calibre of each concert is hard to fault. In recent years festival directors Hugh Macdonald and James Waters have appointed an annual artist in residence, offering said artist several concerts to explore various facets of their creative personalities. Last year was the turn of oboist Francois Leleux, a marvellous musician who isn’t anywhere as well known in the UK as he should be.

This year features not one but four artists: violinists Michaela Martin and Daniel Austrich, violist Nobuko Imai and cellist Frans Helmerson — collectively the Michelangelo Quartet, an ensemble of individuals who each has his or her own solo career but who come together with a stunning group sensibility and musical inquisitiveness. An added factor to the Michelangelo makeup is that Martin and Helmerson happen to be married to each other. They laughed when I asked them what their relationship does for the wider group dynamics: do they channel their domestics through their Dvorak rehearsals? “Ha!” said Helmerson. “I guess you’re married you don’t tend to be very diplomatic. I think we might be more, well, blunt towards each other in rehearsal than most colleagues are…” At which point Martin cut him off. “Exactly,” she said. “Exactly! It’s ideal. It’s efficient.”

Clearly the group is robust enough to handle that non-diplomacy: the playing is superb. For a reminder of what the Michelangelos can do I revisited some of Michael Tumelty’s words about them in this publication. When they debuted in Perth in the spring of 2012, he admired them as “gob-smacking musicians”; that same autumn after the launch of their first-ever Beethoven cycle, he was equally elated. “The Michelangelos are one of the great string quartets of the era,” Tumelty wrote. “Michelangelo’s playing was out of this world.” Perhaps most telling is that by the end of the cycle he was still every bit as hooked, admiring the quartet’s “razor-sharp form” in the fearsome densities of Beethoven’s Opus 130.

It turns out that the Perth experience was special for the Michelangelos, too. Now they are half-way through another complete Beethoven cycle in Toyko, but “even if we play the whole set a hundred more times over, that first cycle will always be important for us,” Martin said. “It was a very real and very palpable journey with the audience.”

At Lammermuir we’ll hear each of the Michelangelo members in solo guise: Martin and Imai in Mozart’s Sinfonia Concertante with the Scottish Chamber Orchestra, Daniel Austrich in Frank and Beethoven sonatas with pianist Danny Driver and Martin and Helmerson in Brahms’s Double Concerto with the BBC Scottish Symphony Orchestra. Meanwhile the three straight-up quartet programmes keep Beethoven as their fulcrum. Each contains one of the Opus 59 Razumovsky set — pieces that stunned their original performers and audience, commissioned in 1802 by a Russian count who wanted to wow his dinner guests with cutting-edge new music. Wow them he did, though he didn’t imagine such intensely volatile works as these. The unpredictable rhythms and abrupt gestures can hardly have made for easy digestion. When even the musicians complained the scores were “not music”, Beethoven responded with the immortal line: “they are not for you, but for a later age”.

For Martin and Helmerson, the Razumovsky quartets represent a cycle within a cycle, a pivot point, a challenge of boundless dimensions. “The intrigue of this music will never fade,” they told me. “Actually, that’s why we wanted to play in a quartet in the first place. It felt such a waste to be a string player and not explore the best music ever written for our instruments.”

Lammermuir Festival is 11 – 20 September at venues around East Lothian