without speakers?? You mean without the external speakers??
The only way to set some other music player as default (or close to it) is by changing the icon on the main menu and re-mapping it via the xml. I'm not too sure if its been done on a
K810.. you could ask number1, he's the
K810 guy around here

You could try different sound drivers and/or make your own ones...
And I'd recommend trying out cam drivers, unless of course, you've already done it.
And radio without headsets just means that the radio player opens up. There is no reception because the headset is an antenna for the radio. So i always found that patch quite pointless you know