How do a pair of DJs give a concert-cum-club night without falling between the two stools? How to satisfy those who want more of those block rockin' beats without selling out those who just want a night of dancing?
Dance music's most visible stars, The Chemical Brothers, tackled this conundrum at The Red Box on Saturday night, and almost succeeded.
They could have just re-created the albums and shouted over them. Option avoided, thankfully. Or they could have done a standard celebrity club night.
Instead they came to an honourable compromise, using a few better-known samples to enliven their now famous big beat rhythms.
Still, the evening didn't get off to a great start. Hundreds of punters must have cursed the anti-drugs security as they queued around the block in the drizzle. Even the clean-living Irish Times and his brother were searched. Chemical-free.
It meant that the place was slow to fill up. Which was just as well because the preamble was frankly rubbish. Four men on stage under what looked like four huge pairs of underpants generating music that sounded like the Utah Saints. One even played a bass guitar. How quaint.
Still, things picked up when the Chemicals made their way to the DJ's booth around midnight, Tom Chemical's T-Shirt sporting the word "Socialist" across its chest.
What followed musically was a curious sort of half-caste, mixing the odd rock star gesture with standard DJing. The audience, a mixture of the giggoing classes and the clubbing silver trouser brigade, didn't know whether they should be dancing or paying attention.
In the end they just danced with their heads craned upwards towards the booth.
The problem was that The Chemicals are lively enough, and get a crowd dancing with imperious ease, but their music is a fraction tedious. To expect any more than the continuous 4/4 dancing beats is to turn a dance night into a spectacle, and destroy the compromise of album and club.
But they are not the same Chemical Brothers without their best-known samples. The Chemicals managed to be both fish and fowl, but still didn't quite satisfy.
The music followed a pattern: several minutes of white noise followed by 20 of jiggy-jiggy, with the odd siren and moderately inventive sample.
One got the feeling that if Eggbreath from Hull had done the same thing, nobody would have thought it was anything extraordinary.