I am trying to connect a desperately dumb samsung tv with a sonos connect. What we need to do is to convert either the sonos optical or analog output into hdmi arc format that the samsung tv can take as input
You are trying to use your TV speakers for Sonos? Won't sound very good but ARC is for getting TV sound out of the TV not getting audio into the TV.
You could try one of these http/www.amazon.com/Tmvel-RCACVS-Composite-Converter-Blue-Ray/dp/B009A6PJKQ
but it may not work without a video signal
Any non HDMI inputs will have L/R audio RCA inputs that can be used with the Sonos if the TV will work without a video signal at the same time.