For those into contracts, 175 East delivered firm promises for its Sunday concert, chalked up on a blackboard, reading "75 min - lockout applies".
In fact, the hour and 50 minutes in Q Theatre Loft was the most testing and trying presentation in the group's 18-year history.
Fine musicians such as Luca Manghi, Donald Nicholls, Andrew Uren, Alex McDonald and Katherine Hebley picked up their instruments just twice.
John Lely's Symphony No 3 (The Parsons Code for Melodic Contour) had them playing random chords, following vague instructions to go either up or down in pitch.
Eighteen minutes proved a long haul, any harmonic fortuities being undercut by too many stuttering entries.