If there is an afterlife, let's hope the journey to it is more like how Rachmaninov imagined it than how Xenakis did. The regretful acceptance Rachmaninov weaves into The Isle of the Dead is hardly something to look forward to – but heard next to the terror expressed in Xenakis's 1980 score Aïs, Rachmaninov's boat trip seems jolly.

This almost mischievously eclectic programme by the BBCSO began with the first Proms performance of Xenakis's 1968 orchestral work Nomos Gamma, a piece written, as the composer stipulates, for 98 musicians distributed among the audience. Here the players were seated in the arena, with conductor David Robertson dead centre and the Prommers crammed around them. Perhaps it was only the latter who got the true surround-sound effect Xenakis was after, but the spacing of the players still made for striking shearing effects as the blocks of sound – fast, blunt drum strikes, brass notes gliding in and out of focus – scythed around the hall, at least for those in the seats low down.

Aïs uses many similar ideas – insistent drums, grumbling bass notes almost too low to hear – but the exhilaration is replaced by panic. Up front, percussion soloist Colin Currie reinforced the momentum, while baritone Leigh Melrose delivered the disjointed Greek text in virtuoso falsetto swoops and cries that all too briefly relaxed into an almost lyrical, keening line in his normal register.

The orchestra was just as convincing in more familiar repertoire. Robertson's flowing tempo meant that the Rachmaninov perfectly evoked the dip and twist of oars in the water. And in Shostakovich's deceptively throwaway Ninth Symphony, the players sounded delicately precise – which, near the end of a long Proms season, was no small achievement.

The Proms continue until 12 September. Details: bbc.co.uk/proms