Official t-shirts and posters were on sale in the lobby and board mixes could be had by the chrononauts arriving anytime between last Thursday and next Friday.
The MC advised everyone to be careful and as dirigible time machines mixed co-ordinates with less conventional moebius runners and tempus fugitrons the band let go with their opening chaos of lights and sound and, with suitable chrono-modulation, music, smpte coded into strobe flashes which had the time vehicles in all their mad inventor's configurations dancing in and out of the vortex of sidereal tenporality so that a distant observer would only have been aware of a single brilliant explosion of noise and light that lasted for less than the time it would take to measure it or register at all.
And the music kept pushing back further into the past, naturally, to make space, since the entire performance was happening that way anyhow.
To the participants, the concert lasted for years, decades, without an apparent break, as the band phased into the next stack of time whenever it pleased them, the audience themselves popped in and out as it suited their individual plans, all synched up relative to each other only instants away from paradox by the all-consuming all-powerful smpte code. Archaic but a universal standard, difficult to replace.
When the concert truly ended, it was because the band had died. Of course, only relatively speaking, for the chrononauts, and the band itself, continued to visit the singularity and watch the show, again and again and again, ever with more participants, until time technology had spanned the universe itself, and everyone who had ever existed with access to time tech was a participant.
It was colossal, universal, immense, populous, gargantuan. So large and massive a pulse in the linear timestream that its moment of totality eventually eclipsed the frame of the concert entirely and with an explosion of coherence, It slipped to the beginning of the history of history.
What began with a heartbeat, ended with the birth of time itself.
But somebody forgot to turn off the amplifiers, and if you tune a radio to the right channel, you can still hear the hiss of abandoned devices of great architecture and unimaginable power.
They wait for the band to return.
T-shirts are still available in the lobby, but unfortunately, the board mix is absolutely, irrevocably, out of stock.
But those T-shirts are wicked, get 'em 'fore their gone, and hurry.
It's later than you think.