Thanks. The wireless joey would be considered the dish box in this case.
You'll connect the joey to your tv via hdmi,
then hook optical out of the joey to the samsung
For the 2nd system, you'd need a bluetooth transmitter: http://amzn.to/1O7GkGZ
That will connect to the red/white ports on the joey, and then be paired wirelessly to the other system.
This will give you sound out of both, but to forewarn you, the sound quality may not be what you expect.
The sound from 2 different systems, especially with different connection methods, is likely to conflict and cause some echos or distortions. In a garage environment, it may not be a big deal though. If you find you aren't happy with the sound from the 2nd system, you'd be better off just leaving it off completely and turning up the volume on the main unit.