I'm not sure about the music channels but I listen to NPR's streaming news using the N810's desktop 'Internet radio' all the time.

I did that by going to NPR.org, and instead of click on the '24-hour Program Stream' icon on the top of the page, click 'Radio' under 'Services' on that navigation bar on the left of the page. Then I select 'NPR Worldwide' and you will see an option to 'Please set a preferred player for NPR audio..'.

I picked 'Real' and N810's media player will launch, then you can just 'bookmark' that stream and afterward this station will show up as an option on the desktop 'Internet radio' widget.

Hope this is helpful and good luck.