Thanks for your prompt response (I only saw this today!) I have tried both of your suggestions, and neither have worked. I have (and always have) saved the instance with the Playback Devices, and the Score. When launching an instance, it ignores the setting. I have set up Sibelius exactly as you have suggested, to no avail.
Here are some hints as to what might be going on:
1. Silbelius (or rather, VE Pro 5) always *tries* to launch the correct playback configuration. For some reason, it always gets interrupted with the odd cembalo configuration. This is the same regardless of what configuration I try to load, and also when I start Sibelius without a VSL instance at start up (as you suggested).
2. I *did* have such a cembalo playback configuration in the past.
3. From 1 and 2 above, I feel there is some stray playback configuration lost in the file hierarchy that is causing the issue. I have tried all sorts of user defined preference files with both Sibelius and VSL. The only success I have had, is when I delete all the playback configuration files in User/Library/Application Support/Avid/Sibelius 7/Playback Configurations.
4. 3 above resolved the situation for a short period - at least one start up session! But after that, somehow the cembalo configuration manages to rise from the dead and dominates the playback configuration, much to my amazement.
My conclusion is that there is some kind of file either with Sibelius or VSL that needs to be deleted and refreshed. So far, all I need to do is close the odd cembalo configuration and open the appropriate one, but this is a hassle after a few times.
Apologies for the long-winded discussion, but any thoughts from your side would be highly appreciated! :)
Thank you and best regards -