In search of relatively rare fabulous beasts like César Franck’s Piano Quintet – given a fantastical performance last night – you often have to take in the ubiquitous Shostakovich specimen, the modest work of a master using simple means to his own creative ends that doesn’t bear too much repeated listening over a short space of time.

This Palm Sunday served up an epiphany. Previous encounters with Handel's Messiah, in whatever version, and whether listening or performing, turned out to have been through a glass darkly. And here we were face to face with undiluted genius, served with total consistency by 26 musicians running the gamut from intimacy through fury to great blazes, all guided by the extraordinary spirit of IBO artistic director Peter Whelan.

When your special guest is a young soprano with all the world before her, the total artist already, your programme might seem to run itself. Yet the Dunedin Consort’s sequence seen and heard in Glasgow, Edinburgh and (last night) London followed a proper musical logic, running together an overture, a ballet and a cantata in the first half, and pulling focus on Handel’s early years in Rome, all supremely inventive music – though the later G minor Concerto Grosso which launched the second half is in a class of its own.

Stefan Zweig once wrote that the difference between Busoni and every other pianist he had ever heard was the way the influential Tuscan-born Germanophile performer, composer and intellectual would always appear to be listening so intently to his own playing, “his uplifted face full of blissful rapture, which turns to stone in sweet awe at the Medusa-like beauty of the music.”

In a recent interview with the New York Times, Jean-Efflam Bavouzet mischievously described interpreting Haydn’s piano sonatas as “putting clothes on a rather naked skeleton… You have this joy of bringing it to life with all the tools you can imagine.”

It’s not often that the most bittersweet moment in a rich concert comes in the encore. Elisabeth Leonskaja had already played the generous extra in question, the Dumka movement of Dvořák’s A major Piano Quintet, with the Staatskapelle Quartet only a fortnight earlier. Here, fine-tuned with the Jerusalems, that moment when the joyfully flowing episode turns dark and the piano seems to call from a dark wood proved sheer magic.

What a difference a piano can make. Boris Giltburg, like Angela Hewitt, prefers a very special Fazioli over the Steinways which dominate the concert scene at the Wigmore Hall and elsewhere. While those may yield a greater depth of field, more appropriate for a 2000 seater venue, few pianists have wrought sound magic on them anything like the kind we heard throughout last night’s rich recital.

It’s dangerous to claim a sense of absolute rightness about a musical performance; that could mean no more than responding to an interpretation which happens to chime with your own subjective expectations. Yet I’m happy to stick my neck out and say that the partnership of septuagenarian pianist Elisabeth Leonskaja with the young Staatskapelle Quartet of Berlin felt absolutely right in works by Brahms that cry out in every bar for authentic musicianship (★★★★★).

The Castalian String Quartet is half what I remember, but only literally: while viola-player Charlotte Bonneton and cellist  Christopher Graves may have departed, their replacements, Ruth Gibson and Steffan Morris, more than earned their laurels in last night’s stunning programme.

I am proud – if surprised – to continue to be pretty much a lone voice in the wilderness singing the praises of the composer Guillaume Connesson (b.1970), whose substantial new string quartet “Les instants retrouvés” was heard at the Wigmore Hall on Saturday.