The brass of the Cincinnati Symphony Orchestra burst upon the finale of Shostakovich’s Symphony No. 5 with electrifying power. It was the summit of a gripping performance led by Louis Langrée to open the orchestra’s season on Thursday night.

The celebratory evening included cheers, standing ovations and a stunning performance by guest pianist Emanual Ax in Beethoven’s “Emperor” Concerto.

It was also a test of the 2,200-capacity Taft Theatre, Downtown, the temporary home where the orchestra will perform this season while Music Hall undergoes a $137 million renovation. Although the acoustics were greatly improved from an open rehearsal held last January, the hall gets mixed reviews.

What a joy it was to hear Ax, who was observing the 40th anniversary of his first performance with the Cincinnati Symphony. Beethoven did not give the name “Emperor” to his Concerto No. 5 in E-flat Major, composed even as Napoleon was occupying Vienna. Nevertheless, it is the most magnificent of concertos, and Ax was a superb interpreter.

From those glorious opening runs and arpeggios that Beethoven gives to the piano, it was clear that this would be a masterful performance. There was a wonderful clarity and presence to the pianist’s sound. Ax played with exciting precision, even in the most treacherous passages.

A more bombastic pianist might have overwhelmed the orchestra in this hall. But Ax summoned orchestral sonorities without any sign of harshness, tackling great fistfuls of difficulties with finesse. Best of all, his playing was heartfelt, with warmly shaped themes and lyrical moments that shimmered.

His phrasing in the slow movement was sheer poetry. The pianist’s dialogue with the orchestra was magical, and he communicated every note with singing tone. The dance-like finale was exuberant, yet his phrasing was always imaginative.

Langrée was a sensitive partner, and balanced the orchestra well. With the crowd on their feet, the pianist performed an encore of intimate beauty: Schumann’s “In the Evening” from Fantasiestücke, Op. 12. It was unforgettable.

After intermission, the orchestra, which included piano, celesta, two harps and expanded percussion, filled every inch of the Taft’s stage for an equally unforgettable performance of Shostakovich’s Symphony No. 5. Written in 1937, it is subtitled “A Soviet Artist’s Reply to Just Criticism,” Shostakovich’s answer after Stalin condemned his opera, “Lady Macbeth of Mtsensk.” Far from bowing to Soviet pressure, though, it is both tragic and uplifting, and remains one of the great symphonies of the 20th century.

Certainly the bombastic finale strikes the optimistic chord that the Soviets wanted, with heroic themes in the brass, and powerful, incessant pounding on the timpani (Richard Jensen). But Langrée excelled also in finding the melancholy of this symphony. In the first movement, one was instantly plunged into its emotional depths. The strings communicated its angular themes with bleak color, between searing buildups by the brass.

The conductor led with momentum, yet also allowed soloists the time to breathe. They responded with fine playing. There was the extraordinary atmosphere of the lone violin (concertmaster Timothy Lees) against only a celesta (Michael Chertock) at the end of the first movement. An insistent tune in the winds brought out the sarcasm of the scherzo. In the Largo, oboist Dwight Parry’s desolate theme against pianissimo tremolos in the strings was extraordinary.

The brass-filled finale was a glowing summation, and there were cheers at the cutoff.

As for the acoustics of the hall, there was clarity to the sound, but what was missing was the warmth and blend that we are accustomed to hearing in Music Hall. I sometimes couldn’t hear the higher overtones, as well as the mid-range of the orchestra. From my seat in the balcony’s left side, the cellos sounded distant, as did the spectacular trumpet passages of the Shostakovich.

The Taft has had more than $3 million in upgrades. However on Thursday, concertgoers complained of the heat, despite a new air conditioning system. You can likely expect more “tweaking” as the season progresses.