An idiom used to describe the moment of downturn for a previously successful enterprise/musician/actor etc. A clear, defining point which, when reached, means nothing will be the same again.
Similar to 'Jumping the Shark' or 'Nuking the Fridge'.
From Loud Reed and his wife staging a high frequency dog concert ("an inter-species social gathering").....
Yeah man, they were really playing the high frequencies that time.