As far as I can see from my tests, pressing the +/- buttons on the top of the N800 while playing internet radio, it increases and decreases the audio volume, while this doesn't happen if I am playing music through the FM Radio. It is only available when using the full screen app.

Any advice?

Correct.
By the way, I succeeded to have the radio working (headset plugged) and the sound through the speaker!
If I remember well, this happened when I pressed the "power" top button while the volume control window of the radio applet was in focus. It more or less locked my N800 (I had to remove the battery), and afterward, no way to listen to radio with my headset!
After multiple reboot it went back to normal situation.
I didn't tried to reproduce it, but it seems it is possible to have headset plugged and the sound going through the speaker.

Well, you just have to press the button with the key (adjust..?) then the full screen app will appear. Then on the bottom left corner you can choose whether you want the sound through the speaker (speaker icon) or through the headphones (guess what? Press the headphones icon )

Or is it something different that I did not understand?

Omar

LOL, excellent! I never noticed that before.
So I don't know how I succeeded to switch to "speaker" mode, but for sure it was not using the speaker / headset icons!

See also this: http://www.internettablettalk.com/fo...ead.php?t=6625

If you click on the maintenance icon in the FM radio applet (to the left of the speaker icon) then you can select between headphones/external speakers.

What's unfortunate is that it doesn't remember the setting, the next time you plug in the "antenna" (i.e. whatever headphone cable you have lying around) it'll go back to headphone mode.