The xx & Wild Beasts @ iTunes Festival, The Roundhouse, London

On a pretty accurate summation of the past year’s most apparent popular musical surges, line-ups don’t get much more accurate than those in the iTunes Festival calendar. Tonight sees a pairing in acts – potentially the festival’s most polar – who both espouse baffling creativity and are near-certain favourites for the following week’s Mercury short-list.

Doubtless many here are newcomers to the yin-yang vocals of Hayden Thorpe and Tom Fleming of Wild Beasts, or at least that’s the impression the quiet din and shuffling feet invite, as they alternate a fragile falsetto and deep gully. Regardless the Kendal boys give nothing short of their souls in performing highlight ‘Two Dancers’, where Fleming’s voice with added reverb makes for an engulfing experience along with the boldly-placed percussion.

Thorpe’s voice is still its startling countertenor but, alas, those who raise some bizarre screams at the site of the giant X being wheeled onto the stage weren’t likely to really give them their due.

Intensity and tricks of the light act as The XX’s dramatic announcement to the beginning of their set, as Jamie Smith in a cap takes to the drum machine and fires up the beats for ‘Intro’, it seems Romy Madley Croft and Oliver Sim are positioning themselves either side of the break between hearts.

There’s still that sense of tentative confidence in the way they play – Romy’s voice growing into a distinct coo on ‘Crystalised’ and Oliver never daring to look anything but intense for the 40 minutes that follow. But it’s captivating. The Roundhouse has become a cocoon of lovers in all shapes and sizes, some lost, some made, most hanging on the words to songs they’ve related to the feeling for nigh on a year.

At times there seems like an oncoming thunder storm in the bass, but ‘Heart Skipped a Beat’ is given a slight bounce, while b-side ‘Do You Mind?’ is simply beautiful in the dual whispers of “night, night, the whole night”.

The smooth compliment of their vocals on record is recreated with poise here but it’s the final and unexpected mix into ‘Infinity’ that takes the trio from quiet pillow talk to the craft of a classy and affective live act.