Spotify Connect Not Playing Offline Songs To Home Stereo

[novaf4]

Here's the set up:

Macbook Pro Laptop:

- There is an MP3 file in a folder on the laptop.

- Spotify PREMIUM account.

- Spotify 'Local Files' folder set to view that MP3's folder location on the laptop. I.e. the MP3 can be seen in 'Local Files'.

- A playlist has been set up in Spotify (called 'Songs Not On Spotify'), set to 'Offline' with the MP3 dragged from 'Local Files' to the playlist.

iPad Mini3:

- Spotify fully synchronised with Spotify on laptop

- the MP3's playlist ('Songs Not On Spotify') set to 'Offline'.

Result?

I can play the offline MP3 on both devices. Great! (obviously the iPad has 'downloaded' it)

But, I can't play the MP3 on my Cambridge Audio Network stereo, which has been set up to play any Spotify track using my laptop or iPad - using the Spotify 'Connect' facility.

Conclusively, my stereo plays every song I have on my Spotify from the laptop and the iPad EXCEPT the offline ones.

What's the problem?

Does the stereo need to 'download' the track? In which case it can't. Or is there a fixable problem that one of you geniuses can solve?

Thanks

[novaf4]

No one has answered but I've worked it out. Spotify Connect does not play offline music because it is obtaining the music from the Spotify server, not playing any music that have been searched for and saved as playlists on the device. Altenatively, the 'Airplay' feature DOES play offline music, so for me it's a case of setting my MacBook 'Sound' preference to that of my stereo and then choose 'Airplay' on the Spotify app. That works, althought there is an annoying 3 second lag when using any command (volume, pause, play etc.)