Iframe select sound card

[Johans]

Hi, I’m using I-frame to display contents os my local webpage, which works fine.
On this page, I have some links to radio stations.
When I start a radiostream, sound comes through speakers on my display, while it should come via my external USB sound card, as this one is set as default.
When I play a simple MP3 from a directory, Output is fine on the external USB sound card.

How can I set within an I frame that sound should go to the USB soundcard, and not via the HDMI.

[Johans]

@johans
Have found solution myself.
Disabled internal soundcard, so only possible option now is the USB soundcard.