Like its predecessors, the fifth Tête à Tête alternative opera festival certainly doesn't stint on quantity. Each evening is packed with a plethora of shows presented by innumerable groups, ranging in size from medium to small scale. On some dates, it's not possible to catch everything, with one piece playing in one studio while another is in full flow next door. It's praiseworthy as an initiative, but giving (mainly) young artists their head inevitably leads to failure as well as success. So it's scarcely surprising the quality is mixed.

With The Moonflower, a sizable work by the Brazilian composer Mario Ferraro and librettist Eva Daníčková, an intervention at an editable stage might have made a significant improvement. The work has its eco-heart in the right place. Its story is based on the work of botanist Margaret Mee in the Amazon rainforests, and describes her spirit meeting that of the environmental activist Chico Mendes – both articulately represented by actors Laura Harling and Braz Henrique, respectively. But the piece tries to include far too much information. Entire characters are redundant, while Ferraro's neo-Romantic score never seizes the dramatic initiative. Apart from the acrobat playing the moonflower, the staging is rudimentary.

Even more slender was Yellow, an enigmatic if not actually obscure music-theatre piece, whose atmospheric score by composer Daniel Saleeb was its chief redeeming feature.

Making the evening worthwhile, thankfully, was a programme of two works for soprano and ensemble given by Chroma under the astute baton of Christopher Austin. The translucent voice of Sadhbh Dennedy floated gracefully through Marcus Barcham-Stevens's intricate Chinese settings, Dhyana, a tribute to Mahler's Song of the Earth; and David Bruce's brilliantly scored, folk-inspired The North Wind Was a Woman. Both were hugely impressive. Neither, however, was an opera.