Unsuk Chin's music is extravagant. This must have been a shockingly expensive concert to produce. The stage at the Barbican had to be extended to fit the massive orchestra, and the whole middle section of the stalls was closed off for safety reasons. The two intervals lasted longer than usual because there was so much equipment to move. Huge expense, smaller than average audience, even by new music standards. But such is the BBC's commitment to its ideals that this concert went ahead as the high point of a day-long Total Immersion, with other concerts, talks and a film.

If Unsuk Chin's music were architecture it would be like the grand public places in cities, with shining towers and vast plazas that celebrate civic achievement and status. This music impresses because it's designed for maximum impact. Although it's modern, conservative audiences can relate to it, as it isn't specially avant-garde. This is music that attracts arts sponsorship because it fills a niche. Chin's Cello Concerto was a big hit at the 2009 BBC Proms because it spectacularly filled the vast performance space of the Royal Albert Hall.

Similarly, Kala (2000), is dramatic in gargantuan style. Two soloists, Sarah Tynan and Adrian Peacock fronted a huge orchestra and double choir. Kala traverses seven stages, each based on a text that involves word play. The first, Gebet is an incantation of vowel sounds. Peacock's resonant bass makes it seem deeply profound, though the sounds have no meaning, not that it's necessary in a musical context. What a panoply of instruments - two harpsichords, an array of green painted barrels in the percussion. This must have been fun to rehearse, but Ilan Volkov led the BBC Symphony Orchestra and Voices with finesse. Nonetheless, the finest moments were when the singers performed with relatively little accompaniment. Tynan sounded specially pure, projecting over the tumult around her.

Chin's Violin Concerto is one of her most famous works and has won awards. Jennifer Koh brought refinement to the very high tessitura, supported by the shimmering textures of marimba, resonating gongs, and the first violins painting attractive washes of colour. Vaguely gamelan sounds and a sudden flourish on the tambourine. Koh has some good moments, such a swooning, sliding legato that hints at jazz. Perhaps part of this concerto's appeal is its clear debt to György Ligeti, with whom Chin studied. Here are intimations of Ligeti's ethereal textures that soar into extra terrestial stratospheres. Chin's music isn't nearly as original and sophisticated, but the Ligeti connection has served her well.

Oddly enough for such a prolific composer, Chin's Rocana (2008) is her only orchestra work without soloists and voices. The title refers to a beam of light, or a beautiful woman as its emboidiment, so perhaps a solo voice is there after all, embedded into its spirit. Chin herself writes of the interaction of "beams of light - their distortion, refraction, reflection". The relative abstraction of this piece allows it to progress through different perspectives. Light after all, doesn't need form, for its nature is elusive.

Wu Wei, described as "the world's leading sheng soloist" appeared in Chin's Su (2009). In China, the sheng dates back 3000 years, Variations are found in Japan and Korea, and there are versions for large scale Chinese instrument orchestras with extra pipes, range and volume. Wu Wei plays a modern instrument whose possibilities are still being explored. One unusual characteristic is that it can be played with continous inhalation and exhalation - ideal for "circular blowing" and amazingly long lines. Wu Wei impressed with his technique, but I was less taken by the music around him which was fairly straightforward. Towards the end, he duets with what sounds like a more traditional sheng, electronically projected from the top of the balcony. Wu Wei has given the premieres of 150 new works, of which ten are concertos for sheng and orchestra, so I hope we'll be able to hear more of him and the instrument, soon.

Earlier on during this BBC Total immersion day at the Barbican, a film of Unsuk Chin's opera Alice in Wonderland conducted by Kent Nagano in Munich was shown. The texts are by Chin herself and Henry Hwang, crackling with wit and whimsy. It's quintessential Chin, wordplays without meaning, quirky inventions in sound and multiple references - there's even an extended quote from Gershwin's Rhapsody in Blue. Lewis Carroll's narrative gives the music backbone. Sally Matthews as Alice manages heroically, although she's trapped in an enormous mesh head which hides all emotion. Andrew Watt's countertenor creates a huge range of personalities through his voice, and for once, Dietrich Henschel's metallic timbre finds a perfect outlet. Most credit, though, to director Achim Freyer who transforms what might have been a flat staging into a multi-dimensional fantasy with darkly sinister undertones. Perhaps the mesh head Matthews wears expresses something profound in the story the text itself doesn't reach. While the opera itself is a little self conciously full of its own cleverness, Freyer's puppets and grotesques add drama and potency.