This is a developer forum, aimed at programmers.
If the volume button on the phone doesn't adjust the volume of the music, the fault is probably not the bluetooth API, but either the player on the phone, the OS on the phone (if running a custom ROM), or simply that the media volume on the phone is already maxed?
Windows 10 shipped with Bluetooth partially broken. I had to use the Insider Builds just to get a version with bluetooth serial ports working. Are you at least on the latest service pack and fully updated?
Basically, I would be surprised if you actually need Blue Soleil. From what I can tell, it's mostly useful for programmers. Microsoft and other bluetooth stacks support streaming audio. They just don't make it available to programmers for an affordable price, which is why Blue Soleil is useful.
Having said all of that, a new update for the Blue Soleil software came out yesterday. Maybe you'll have better luck with that.
