Well, if Apple gear is an option, the Apple AirPort Express has a digital TosLink optical output, as does the Apple TV 3rd generation, IIRC. Analog output too. Feed into any Amp or powered speaker.

Some powered speakers accept TosLink optical input, so no ground loop concerns.

http://www.theairportwiki.com/index.php?title=AirPort_Express

http://www.harbeth.co.uk/usergroup/forum...-external-dac-s

http://www.imore.com/how-hook-fourth-generation-apple-tv-optical-audio-speakers