Pittsburgh SO / Jansons, Royal Albert Hall, London

Today's sparkiest partnership of conductor and orchestra dropped in for two Proms just in time to upstage Simon Rattle's Berliners. To build one long-term musical relationship is rare, but Mariss Jansons has managed two, first in Oslo and now in Pittsburgh, where he is entering a seventh and last season. Next for him come the contrasting challenges of Munich and Amsterdam.

The Oslo Philharmonic had a Nordic kinship with Jansons. The Pittsburgh Symphony Orchestra, however, delivers a kind of fusion. Latvian conductor schooled in Russian traditions meets US orchestra big on brass and discipline, and they thrive on their complementary qualities. What results has a larger-than-life character. It's loud, precise,generously expressive, and sometimes delicate. The strings have ample weight, but the stars are the woodwind, particularly oboe and bassoon.

Beethoven's Second Symphony sounded traditional, in the sense that you might have heard it from an American orchestra 50 years ago: full-toned, emphatic, invigorating rather than exciting, good-humoured rather than witty. The slow movement sang like Schumann or Mendelssohn, the strings indulging in a few portamento slides. This was playing full of character, an upbeat foil to the Tchaikovsky Fourth that was to prove the high point of the visit.

For this, the expansiveness remained while the atmosphere was immediately doleful, and the progress of the symphony became tragic rather than the sequence of unstable mood-swings it often can be. You admired a superbly controlled gradual acceleration here, a mosaic of sharp characterisations there, but it was large perspectives and steady accumulations that underpinned the performance. The finale's crisis was prepared by stealth, its turn to despair not inevitable but genuinely shocking.

Gil Shaham played the Mendelssohn Violin Concerto to open the second night. His projection of tone matched the orchestra's weight, and they had to play faster and lighter; the impact was brilliant and direct.

Jansons in Mahler is more of a culture clash. He relishes the effects and orchestral virtuosity but often seems to remain on the outside. You feel you are observing Mahler's soul rather than entering it. Symphony No 1 was done rather like a concerto for orchestra, as Jansons played with detail and phrasing. The trumpets delivered biting interjections and, in the evocations of popular Jewish music, an eerie vibrato that went beyond parody.

Not everything was so idiomatic, but it was compelling, and towards the end the soulful character came across more strongly, thanks to woodwind solos in the quieter moments. At the end, the horns were so dominant that you could hardly miss them, but they came in with a dramatic suddenness that reinforced the music's sense of ascendancy.