Hmm, maybe it's an issue with your default setting of sound device.
Try right-clicking on the speaker symbol in the lower right corner on your desktop page, and choose 'Playback devices.' Select another speaker device - i.e. the one corresponding your DAC/digital output - and set as 'Default.' Then try playing your web-based sources.
Normally, with playback from JRiver, I choose another playback device(than the one I actually use) as 'Default' in the Windows setting, as I have already specified my playback device(DAC/digital out) in JRiver's settings, and using a direct-mode output format like ASIO or WASAPI the JRiver software then has exclusive access to your DAC(via whatever specified digital out is used) - meaning no other source than JRiver can access your DAC. Maybe that's your "problem," in this case, that you need to give your web-based source at least temporary access to your DAC by re-setting to your actual plack device(your DAC/digital out) in the Windows setting.
