Hi @GlynHoward.

Welcome to the Sonos community and thanks for reaching out to us,

I would like to share with you this guide on Sonos S2 compatible Sonos devices for us to better uderstand what Sonos devices will and will not work with the Sonos S2 and S2 app. To answer you question directly, it is a yes. The IKEA Symfonisk bookshelf speaker will work on Both S2 or S1 app but not both at the same time.

I hope this helps.

please let us know if you still have further questions or concerns. We are always here to help.

Thanks,