Offline playing in high end app

[drftr]

Hi,

I'm looking for a good music web shop but will play all my downloaded music offline through a high end device.

Can I use Spotify downloads for this? As far as I've read I would be limited to using their apps for this, which is not an option.

If not possible, are there other music services that allow downloads to be played with top class devices?

Thanks a lot!

drftr