“Improvisation? That?” whispered a Japanese lady to her friend at the end of the afternoon concert. She was making a good point. Half the performers in this programmed jam were glued to their scores. It was the low point of a mixed day at the Barbican Centre that began with a very enticing premise of offering to immerse us in the “Sounds from Japan”. We barely dipped our toe. The problem wasn’t simply the variability of the music; it was also the laziness of the curatorial thinking.

I’ve seen some double acts in my time, such as the Oistrakhs and the Torteliers, but none quite like that of Storgårds and Hardenberger. Best friends, they took it in turns to conduct the BBC Philharmonic and to take over the soloist's spot. First one mounted the rostrum, while the other gave us a UK premiere as soloist. Then they switched roles, producing a second UK premiere.

John Cage 100 Various artists (Wergo)

Viennese night in Glasgow’s Candleriggs was hardly going to be a simple matter of waltzes and polkas. True, its curtain-raiser was a Blue Danube with red blood in its veins rather than the anodyne river water of this year’s New Year concert from Austria’s capital; one would expect no less from Donald Runnicles after the refined but anaemic Franz Welser-Möst.

The tabloids are getting shriller every day in their warnings about the army of Bulgarians and Romanians about to descend on British shores, so it’s probably lucky that none of their journalists was present last night at the Barbican to witness an Eastern European musical coup of deadly efficiency. Kristjan Järvi and the London Symphony Orchestra may have cleared the path with a little help from Enescu and Kodály, but it was Bulgarian virtuoso performer-composer Theodosii Spassov – playing an instrument no one had ever heard of – who routed us completely.

The centenary bandwagon always passes some composers by: how many organisations in Britain will be celebrating George Lloyd or Tikhon Khrennikov? Other figures almost get steamrollered flat with attention; Britten, I’d say, is this year’s likely candidate. But who could throw any stones at the birthday cake and bunting created by the Philharmonia Orchestra for that mercurial Polish wizard Witold Lutoslawski?

Period instruments demand absolute honesty from their players. Their sound is their personality - candid, quirky, eccentrically beautiful - but their soul is revealed in the spirit of the playing, where beauty is not skin deep and the expressiveness of phrasing in the strings is created in the bow arm and from a truthfulness of intonation that does not hide behind vibrato.

Kings Place’s Bach Unwrapped season invites audiences to come at the composer from new and unexpected angles. Bach gets arranged, adapted and re-orchestrated, and his legacy is showcased in works from three centuries. Occasionally however he also gets played straight – and it doesn’t get much straighter or more authentic than the Academy of Ancient Music and the Choir of King’s College Cambridge performing the St Matthew Passion.

And so John Adams’s residency with the London Symphony Orchestra reaches its finale – a brisk allegro of a concert with a cheeky coda in the form of the composer’s latest orchestral work, Absolute Jest.

We’re still in the foothills of the Southbank Centre’s year-long The Rest is Noise festival, but already the harmonic ground is becoming unsteady underfoot. Last weekend saw the gemütlichkeit of Johann Strauss give way to the brutality of Richard Strauss, exposed us to the moistly chromatic flesh of Salome that lies behind the seven veils, and showed just a hint of Schoenbergian ankle. So surely this weekend’s return to 1900 and Elgar’s choral-society-stalwart The Dream of Gerontius is something of a retreat?