i tried to look for a 5.1 amplifier only for the output from TV (not a reciever) with smart tv's who needs a reciever? nobody has this type of device. But . if you aren't looking to develop a product, here is what i found on ebay. that i am going to use for the same purpose
5 1 Ac3 DTS HD Audio Decoder Digital Sound Decoder Optical SPDIF Coaxial to 6RCA | eBay
and this 5.1 amplifier board with just simple volume controls
TDA7498E x3 5 1 100W x6 Class D Amplifier Board WLX | eBay
This was everything goes into the TV via HDMI , laptop, blueray, cablebox, videogames
and the output from TV goes to the decoder and amplifier. Escpecially nice for these new internet ready TV's who needs a "reciever"