Philadelphia Orchestra / Eschenbach, Barbican, London

Shock and awehave infiltrated US musical life, if a pair of concerts given by the Philadelphia Orchestra at the Barbican under their newish music director, Christoph Eschenbach, is anything to go by.

Shock and awehave infiltrated US musical life, if a pair of concerts given by the Philadelphia Orchestra at the Barbican under their newish music director, Christoph Eschenbach, is anything to go by. True, Schoenberg made two versions of his revolutionary string sextet Verklärte Nacht for string orchestra, but the jump from six players to 60-plus - the entire Philadelphia string section - seemed a grotesque exaggeration. Gone was the intimacy of the original - a tone poem for the smallest of forces, with the subtlest of colours and intricate contrapuntal lines, extending and expanding Wagner's harmonic and Brahms' metric developments. Who could have imagined, from the overheated opening it was given by the Philadelphia, that this work inspired by Richard Dehmel's poem begins spookily in forest moonlight?

Eschenbach is just completing his first season with the Philadelphia. The orchestra has an enormous sound, but under Eschenbach this seems to be its defining quality. Variety of colour and subtlety of phrasing don't seem high on his list. In Mahler's First Symphony, while brilliantly judging dynamic balance, he seemed strangely uninterested in bringing out the astonishing thematic detail of the score or emphasising Mahler's disturbing colours. And, as in the Schoenberg, the power of the overall architecture was undermined by Eschenbach's pacing - too much, too soon.

The second concert brought Brahms' Violin Concerto and Shostakovich's 10th Symphony. My suspicion in the first concert that Eschenbach has no ear for the bass line was here amply confirmed. He looks ahead or to his left, continuously rousing his first violins with fussy, militaristic gestures, while shunning his cellos and basses.

And how it shows. Brahms without underpinning makes no sense. Important rhythmic figures are left under-articulated and haunting chromaticisms ignored. This concerto was once described as being written "against" the violin, but in Gil Shaham we had a soloist totally unfazed - indeed, a little more struggle might have been welcome. The brilliance too easily became pat. If Eschenbach could have taken a back seat, orchestra and soloist might have had more fun.

Shostakovich's 10th is one of the most harrowing scores ever written. This is a work whose emotional impact is shattering. The appropriate response to a performance should be to creep away, humbled, fearful. But not, alas, here. Eschenbach seems to lack any emotional understanding of this work. Where was the ambiguity, the irony, the understatement? Time and again, moments of tremendous tension went for nothing, the building blocks not in place. Impossibly, a jolly encore ended the evening. It said it all.