The final week of the 2011 Proms season began with a flamboyant and exhilarating concert given by the superb Pittsburgh Symphony Orchestra, who celebrate their 110th anniversary this year. They were joined by pianist Hélène Grimaud, playing Beethoven’s Fourth Piano Concerto, the piece with which she made her Proms debut in 2001.

I do not envy any musician playing in the Albert Hall, with its size and uncertain acoustic to contend with. (An orchestral violinist I met recently told me it was like “playing alone”.) But the Pittsburgh Symphony Orchestra, under Manfred Honeck, threw down the musical gauntlet from the very first bars of the opening piece, Walter Braunfels’ Fantastic Visions of a Theme of Hector Berlioz, a work composed before the outbreak of the First World War, but premiered in Zurich in 1920. It must have raised the spirits of its war-weary audience: not only “fantastic”, but energetic, weird, humorous, mocking, grotesque, jubilant, filmic and swaggering. For his theme, Braunfels took the Song of the Flea from Berlioz’ Damnation of Faust; for his scoring, he demanded a full orchestra. The Pittsburgh Symphony Orchestra filled the hall with sound, a big sound, rich and warm, with lush strings, ripe, fruity woodwind and downright “rude” brass at times. Under the precise and dynamic direction of Manfred Honeck, this was a rousing and lusty start.

With the massive orchestra significantly down-sized for the Beethoven concerto, the piano was wheeled onto the stage, its lid raised to the customary collective shout of “heave ho!” by the prommers.

In his Fourth Concerto, we have Beethoven the radical, as the opening of this concerto is astonishing: for almost a century before, concertos had always begun with an orchestral introduction. Beethoven breaks with tradition and gives the piano a five-bar introduction, an opening phrase, eloquently articulated by Grimaud, which is left hanging and is immediately answered by the orchestra alone. This sets up a very special relationship between orchestra and piano, which remains a constant throughout the work.

Grimaud has a reputation for being a “risk taker”, but at no point during her performance did I fear for the music. She demonstrated an insightful and imaginative understanding of this work, and skillfully capitalised on the dualism of the music, neatly balancing the compelling and the commanding. This was particularly evident in the first movement cadenza, which glittered with a Mozartian clarity while also demonstrating the forward-pull of Beethoven’s revolutionary vision in sections of pure weirdness and unpredictability.

In the middle movement, the portentous tread of the orchestra’s opening motif is offset by a controlled recitative from the piano before orchestra and piano engage in a direct dialogue, the orchestra wild and angry, the piano offering a soothing hymn in response. Here one really felt the special synergy between orchestra, soloist and conductor that the music dictates, but there was also the sense that they were all old friends.

The final movement, a rousing Rondo, with its wonderful, memorable theme, prickled with energy and wit, Grimaud proving that she can do powerful rhythmic playing as well as songful lyricism. Again, in this movement she opted to offset the solidity and simplicity of the classical ideal, evident in the architecture that underpins this glorious movement, against Beethoven’s dramatic innovation: here we see a composer poised on the cusp of change. Vital and emphatic, Grimaud let loose with an excitement and emotional richness that never obscured the music itself. The applause, which came almost before the last note had been played, was utterly spontaneous, generous and deeply appreciative.

In Tchaikovsky’s Fifth Symphony, a work imbued with an openness, a sweeping romanticism and more heart-on-the-sleeve emotions than the introspective, self-obsessed Fourth, we heard again the wonders of the Pittsburgh Symphony Orchestra’s brass and woodwind sections, the lush silkiness of the strings, an almost chocolatey sonority in the double-basses. From a first movement, which was dramatic and textural, through a third-movement Waltz that reminded us that Tchaikovsky was a composer of ballet music, to a finale, a vigorous Russian dance, this was a colourful, exciting and absolutely convincing account. The brass shone, the woodwind haunted, and both sections were afforded special applause, richly deserved, at the end.

For a first encore, the Entr’acte from Bizet’s Carmen allowed us to indulge further in the gorgeous woodwind and the fine balance between all sections of the orchestra. The second encore, the Galop from Khachaturian's Masquerade Suite no. 5, played after much unison hand-clapping and stamping by the audience, was a rambunctious frolic, a musical raspberry blown to lighten the mood, which matched the exuberance and humour of the opening piece perfectly.