Old instruments have found young champions this week in two very different concerts and contexts. In the Wigmore Hall, Mahan Esfahani continued his persuasive rehabilitation of the harpsichord, showcasing not only the expressive range of the instrument itself but – more unusually – its repertoire, in music from Byrd to Ligeti. Meanwhile out in Richmond young singer-songwriter Joseph Reuben took a string quartet on a stylistic journey, blending classical textures and processes with an indie-pop sensibility to create a thoughtful fusion.

The Barbican Hall’s house lights faded to black, with just the soft glow of music stand lamps on stage as the Britten Sinfonia filed on and eased into the Adagietto from Mahler’s Fifth Symphony. Directed from leader’s desk by Jacqueline Shave, the orchestra gave an exquisite account of the piece, the chamber aesthetic and necessary communication between players somehow helping to draw the audience in. It was certainly a rewarding alternative to the lusher – and slushier – version one would hear from a full symphony orchestra’s worth of strings.

Blether on MasterChef about love and passion for one’s craft has so devalued the currency that I hesitated in applying the terms to conductor John Wilson, last night moving from Hollywood and Broadway to another enthusiasm, tuneful British music. Yet who merits them better than he?

“Did he who made the Lamb make thee?” Blake asked the tiger. One might have asked the same question of Scriabin’s Poem of Ecstasy, with Mozart’s G major Piano Concerto, K.453, as the lamb, in this hyper-diverse Birmingham concert. The image of divine simplicity was in the delicate hands of Mitsuko Uchida, whose Mozart resisted every striped temptation that Andris Nelsons and the CBSO threw in her path.

Vladimir Jurowski deemed this the most challenging of any programme in the Southbank’s year-long The Rest is Noise festival and proceeded to tell us precisely why. That his little preamble lasted almost twice as long as the first piece - Webern’s Variations for Orchestra Op.30 - was an indicator of just how scientific the thinking behind his programme was. Jurowski instinctively understands how and why works impact on each other in the way they do.

Highly sexed cockerels and cats, a lovesick lion and a ballet of frogs might not seem like a recipe, or rather a menagerie, for profundity. Yet in two ravishing French man (or child)-meets-beast fables for the stage, Poulenc and Ravel are quite capable of tearing at our heartstrings. That they did so unremittingly last night was very largely due to the supernaturally beautiful sounds master conjuror Stéphane Denève drew from the BBC Symphony Orchestra.

Backed up by reasonably adventurous orchestral programming, lucky conductors can forge a strong Stravinsky evening by picking and mixing from his five ancient Greek rituals. Sir John Eliot Gardiner, unintentionally homaging the late Sir Colin Davis who at least in earlier days would have jumped to such a pairing, chose to celebrate his 70^th birthday with the extremes of white balletic lyric poem Apollon musagète and hard-hitting blackest tragedy Oedipus Rex.

Visiting orchestras and conductors often complain about agents’ insistence that they programme their main national dishes. The request is partly understandable: we all want to hear the Vienna Philharmonic in Mahler, the Czechs in Dvořák, the Hungarians in Bartók. On this occasion, it seemed like no bad thing to welcome back the Budapest Festival Orchestra and its febrile, masterly music director Iván Fischer in a work they’ve brought to London before, Bartók’s Concerto for Orchestra.

It was clear that there was an Italian on the podium. Muted strings invoked an atmosphere so crepuscular that, when one involuntarily closed one’s eyes, the murmur of voices intoning the words “Requiem aeternam” seemed to come from deep inside the cathedral. The theatricality of Verdi’s Messa da Requiem is inescapable but what was also inescapable under Daniele Gatti’s baton was that every phrase, instrumental and vocal, is breathed as a singer might breathe it.

Brave old world, that has so much unheard music in it. Not exactly the words of Shakespeare’s Miranda, I know, but that’s how I feel having experienced great things in the concert hall for the first time recently: Tippett’s Second Symphony from Martyn Brabbins and the BBC Symphony Orchestra last night, and earlier in the week more self-styled “musical toys” from overnight sensation as Newcomer of the Year at the BBC Music Magazine 2013 Awards Mei Yi Foo: a gallimaufry of piano miniatures by Bartók, Benjamin, Fujikura, Lachenmann and Unsuk Chin.