I see. Well you didn't really ask much of a question, you just complained. We interpreted what you really wanted as best we could.
Why don't you try stating clearly exactly what you're doing, the steps you take to switch the audio output device to your Bluetooth headphones, and the actual error message you get. You keep referring to this error, but you never say exactly what the error message is. Quote it word for word, or a screenshot. Maybe use the occasional capital letter so your post is easier to read.
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Screenshots would help, especially of the audio section of the JRiver options dialog, and of the output format section of DSP Studio.
I assume when you listen to Amazon or Netflix, it's through a web browser? You didn't say.
You also didn't say if you can listen to regular audio files with your headphones in JRiver, or if your headphones don't work in JRiver at all. You only mentioned bluray. Do you get the same problem with standard definition DVDs too or just bluray?
As you can gather from my questions, there's a lot more helpful information left out of your post than you put in. Help us help you.
There's nothing special about headphone output. Windows presents headphones just like any other audio device, and all Windows audio devices have their share of glitches and limitations. You think because
you can't figure it out that it's rocket science, but I can assure you that's not the case.
Awesome Donkey and I are not employees of JRiver, we're trying to help you out of the goodness of our hearts, so keep that in mind.