I use an echo 3rd gen for audio and it works well. Haven't tried pairing 2 for stereo, but I imagine you'd get a better effect with 2 rather than 1 echo studio. I also have the studio, and while it's a good speaker, you can't replicate true stereo sound with just one speaker.
Plus if you get the 2 3rd gens you can always add the echo sub somewhere down the road.