I would like to listen to SomaFM using the 2.1 speakers at my home .. but without using a computer. Is this possible?
No, this is not possible. You need a "computer" of some kind.
It doesn't need to be a full-blown desktop or laptop PC, though. There are lots of consumer electronics devices that can play internet radio, as long as you have an available network connection for the device.
But you do need a computer: at minimum you need a networking stack, a microprocessor, and RAM and Flash memory (for the firmware/OS). You also need some sort of DAC to output to your speakers, but some CPUs include this on-chip. Anything with these components technically counts as a "computer".
It sounds like a strange request, but I have seen 'Internet Radios' on sale here in Australia.
They presumably use wireless Internet access to access the internet radio stations.
I don't expect to see these things much in the future, because Australians are seeing the introduction of Digital Radio at the present time.
I think you'll have to extrapolate these observations to your own situation.