Help with Cable Box Optical or TV Optical Connection to the DAC

My TiVo cable box is currently connected to my DAC using an optical cable and my Sony Blu-ray player is connected to my DAC using a coaxial cable. The DAC is connected to my Ayre AX-7e integrated amplifier using balanced cables (XLR). The source button on the DAC controls the input selection.  

My local retailer recommends I connect my TV "direct" to the DAC using an optical cable and eliminate the cable box and Sony player cable connections to the DAC.   The cable box HDMI cable going to the TV and the Sony player HDMI cable will carry both video and audio signals. The optical cable from the TV to the DAC will carry the audio signal.

My current thinking is I prefer a DAC that includes both optical and coaxial inputs. The retailer wants me to replace my existing Musical Fidelity M1 DAC with the Ayre Codex DAC that only supports one optical input (it also has USB but it is not required). This change to use optical audio outputs from the TV to the DAC would make the Ayre Codex DAC a possible solution. My question is not if I should buy the Ayre Codex DAC but if I should take the audio signal from the TV to the DAC using the optical connections (in addition, the retailer highly recommends the Ayre Codex DAC and states "this is a remarkable DAC").

I am not convinced that routing the audio signal from the TV to the DAC would result in the best sound quality.   What conversion is going on in the TV to convert the HDMI signal to an optical signal (if any)?   Will the routing of the audio signal thru the TV impact the sound quality?   I believe the audio signal coming direct from the cable box to the DAC will result in the best possible sound.  

Your comments and suggestions are requested.

I tried connecting my Comcast Cable box's Toslink to my DAC and it would not work, regardless of the box settings it would only send 5.1 Bitstream to my DAC.  That said I connected my TV Tomlin to the DAC.  I set the TV to down mix to stereo and it works perfectly.  The TV's DAC uses a sample rate convertor to upscale everything to 24/48k,  this was proven by playing a CD through my OPPO 103 via HDMI to the TV.  The TV  in turn takes that 44.1k data  and outputs 48k via Toslink to my DAC.   Cable content sounds pretty good regardless of being converted......obviously Blu Ray and Netflix sound better but i'm fine with the way cable sounds.   What I didn't expect is that the cable box attenuates the volume in the digital domain, the TV does not.