Sonic Youth/Antony and the Johnsons, Greenspace, Valencia

Like it's party time or something!

Prior to my arrival, white soul showman Jamie Lidell has already performed, and I arrive to catch Detroit techno legend Derrick May on the wheels of steel. The man behind this eclectic bill is Matthew Herbert, whose own performance, mixing samples (the sewers under Fleet Street, the clucks of factory chickens) with a live big band, is agreeably berserk.

On the Friday, star turns Sonic Youth hold a press conference, with flamenco singer Enrique Morente. Each member of the band has one of the new aluminium Heineken bottles in front of them on the trestle table.

Thurston Moore remains an ageless indie-geek icon, but for the other members of Sonic Youth, the band's name becomes more ironic with every passing year. The grey-haired Lee Ranaldo says next to nothing, and it isn't clear whether he's actually alive.

It's an uneventful half-hour. In an attempt to make things more interesting, I raise my hand and ask a question: "I'd like to know what Sonic Youth think of the corporate sponsorship of music." For what seems like a whole minute, they fall silent, and shift awkwardly in their chairs, shooting me daggers.

I'm not being a bastard. Well, not completely, anyway. I know what Bill Hicks thought. I know what I think (although I'm not above accepting Carling's quids for DJing, and hell, I'm here, aren't I?). I wonder what Sonic Youth, a band famous for their underground principles (but who nevertheless signed to Geffen) think. After what seems like a whole minute, Steve Shelley breaks the silence by raising a can and saying, with a sarcastic cheesy grin, "We hate it!". Then Kim Gordon starts talking.

"We have a tendency to avoid it. It depends on the corporation. You just have to hope it's serving the music instead of the music serving it... and hope that the music pushes the bad vibes of the corporation away." Then it gets weird. "As Americans, it's difficult for us to be political in that way. We live in America, and America's mainly owned by China at this point. Everything you buy is made in China." The press corp glance at each other, baffled. Soon afterwards, a halt is called to the conference.

Sonic Youth's gig is about as dull as their talk. There's some attempt at engagement ("Sister" is for "all you beautiful ladies and gentlemen out there tonight"), and "Kool Thing" - one of, what, five good songs in, what, 20 albums? - lifts the mood, but mainly, the most overrated band of the last quarter-century are going through the motions.

Until, that is, Enrique Morente joins them onstage. Now, obviously, from my Brit perspective, I have no idea whether Morente is the David Bowie of flamenco, or the Cliff Richard. But I do know that flamenco is my favourite form of traditional music bar none, and Morente seems to be a fine practitioner, and Sonic Youth work up a krautrock groove which meshes surprisingly effectively with the haunting tones of Morente and his backing singers.

Mixing alternative rock with Spanish gypsy music would be a radical idea, if Sonic Youth's peers (and superiors) Pixies hadn't already perfected it at the back end of the Eighties. Some bands do this all the time: local heroes Marlango, for example, whose stunning singer Leonor Watling's PJ Harvey-meets-Astrud Gilberto-meets-Sarah Vaughan thing is truly enchanting. Fellow locals Jet Lag, however, are merely proof that Spaniards can do ponderous Coldplay/Athlete dadrock too, and nothing more. Then it's time for the main event.

"Hey everyone! OK!" says Antony of Antony and the Johnsons with a grin, like it's party time or something. Then his fingers spread to play a piano chord, and he begins to sing: "My lady story is one of annihilation/My lady story is one of breast amputation..." A contrast in moods, to say the very least, and one which sums up a bizarre - but brilliant - performance from the Mercury-winning, gender-uncertain gospel singer, which mixes material from his first album ("The Cripple And The Starfish" being an outstanding example) with more familiar tracks from the prize-winning I Am A Bird Now ("For Today I Am A Boy", "You Are My Sister" sans Boy George) and ends, as the album starts, with the gorgeously desolate "Hope There's Someone".

It says something for the power of this man's heartbreakingly vulnerable voice, and the outsider spirituals he sings with it, that he is able to becalm, and indeed enrapture, a warehouse full of 5,000 people on a Saturday night who have already been drinking for several hours.

He's having a lot more fun tonight than at his London shows earlier in the year. Where once he hid behind a wig, tonight he's in a crochet skullcap with a jewelled rim. Where once he was silent, tonight he's talkative.

Sometimes, the contrast between the subject matter and the smiling delivery is jarring, but the audience roll with it. After "Fistful Of Love", an extraordinarily moving song from the perspective of the victim of an abusive relationship, he messes about with a couple of verses of "Somebody To Love" by Queen, then plays a prank.

"I wrote a love song for Shania Twain", he tells us, and OK, we'll go with him so far. Then he starts to sing it. "Oooh, I wanna love you Shania", he sings to the tune of "I Wanna Dance With Somebody" by Whitney Houston, "I wanna feel the heat with Shania..." and everyone laughs, feeling silly for being suckers for such a terrible gag.

"She thought," he deadpans, "it was a bit weird."

Antony and the Johnsons play the Grand Opera House York (0870 606 3595), 23 Nov; Academy Glasgow (0870 600 100), 1 Dec; Academy Bristol (0870 771 2000), 3 Dec; London Shepherd's Bush Empire (0870 771 2000), 5 & 6 Dec