Light fittings shake; wallpaper practically peels itself, yet still the breathtaking bass thunders on. It's a wonder it took someone so long to come up with the idea of combining the basslines of dancehall with the dramatic drum patterns of electronica, so harmoniously matched are they in sub-sonics alone.

UK indie Wall of Sound and Jamaica's Gee St devised the collaborative effort that is Two Culture Clash. The album melds sci-fi soundscapes from this island with the raucous ragga-isms of the infinitely warmer other one. The record works fairly well, but makes much more sense this evening when freed from the confines of the CD and unleashed unto the live arena.

DJ sets from Howie B and the live drum'n'bass of show-closer Roni Size are impressive, but the arrival of the dancehall DJs (as singers are called in the Caribbean) is the main event. The venue may not be full to capacity, but the JA crew appear neither to notice nor care.

The charismatic General Degree turns a hovering crowd into an exultant moshpit; Lady Patra, meanwhile, almost manages to eclipse the sexually assertive How Do You Love? with her barely there batty-riders bouncing about the stage in a blur of bumping and grinding.

Neither are a match though for the rampant antics of Ward 21. The self-described "mentally disturbed" quartet storm the stage, jumping on speakers and into the crowd before demanding that the audience fire up their lighters in respect of "the ganja".

The highlight of the night is the arrival of 50-something toaster Big Youth and his righteous reggae. Dusty lo-fi number Rudie No! really hits hit the right note and the crowd - from head-nodding Rastafarians to chi-chi fashionistas - move en masse to the music.

If the point of tonight was to bring together two countries, then mission accomplished. Whether people's ears will ever recover from the assault of someone hitting the megabass so hard is entirely another matter.