I have a HP proliant pc setup under my TV that outputs optical spdif to a YSP 1000 soundbar.
In anticipation of purchasing an echo dot, I spent the princely sum of £1.60 buying a generic CSR 4.0 bluetooth dongle in the hope of sending the sound from the dot via bluetooth, to the PC and ultimately my soundbar.
Finally, after several days of googling many solutions, installing them (removing them), pairing to the point of exasperation, I have sorted it and provide the details here in case it helps someone else.
The dongle does not come with any software, so you'll need to install the CSR software stack from here
http://www.gleescape.com/posts/3093This on first glance, looks like the final solution but it will not allow any services to run that will play the audio from the dot. What you also need, is a piece of software called "Bluesoleil" current version 10, there are links all over google but as most are dubious, I won't post them here.
Anyway, once the 'full' registered version of Bluesoleil is installed and you remember to "pair" your echo dot, you will get full glourious audio sent by bluetooth to whatever speaker arrangement you have connected to your PC!
Hope this saves someone a few hours of frustration, plus also confirms even a generic 'cheapo' bluetooth stub will function (eventually) with the echo dot.