A to D to Bluetooth to Bluetooth to D to A?

Despite the rise of "wireless" audio, I am not quite clear on the state of Bluetooth (or other wireless methods) for audiophiles if anyone could please help?

I get that there are any number of increasingly high quality "Bluetooth" speakers, but how does Bluetooth compare to other wireless transmission methods?

Also and in particular, as I am not an iPhone or serious iPad user is there any way to start with analogue outputs, or line level outputs (RCA?) to a device that transmits wirelessly?  

To then be received and decoded by a power amp, active monitors etc?

Sonos may be something completely different but so far reminds me of the old Bose Wave radio commercials.

Thanks for any ideas.