Hi Doug,
Like almost all music streaming services we pay around 70% of our revenue through the rightsholders. That means the more music is listened to, the less per play gets paid back, but the service always keeps around 30%. On our current usage for us that's working out at around 40p per hour going back to labels (the Vivaldi album cited here is 2hr 27 mins - hence over £1 for one album play)
Most of our customers also own CD, Download or Vinyl collections so not all their listening is happening through streaming. Some also subscribe to other services as well but find for classical our experience is so much better it is worth an extra subscription for that. Also, classical consumers are less likely to have playlists playing from dawn til dusk. Classical music really suffers on major platforms as usage is diluted by listeners of other genres who typically consume a lot more music. Also, some classical works have very long tracks, which only count as a play on major services.