Cablebox Audio Out to DAC inputs and other options ?

It's usually a lot simplier to go from your TV via optical out to a DAC.  If you only use the Cable box to control the channels then I guess it's about equal but if you use any combination of streaming services, cable TV and off air or console or disc player the TV digital out will simplify your life.

You may also find it convenient to purchase an inexpensive DAC like a Topping just for the TV.  This would avoid having to use the integrated AND DAC switching. 

 I'm not recommending this specific unit, but something like this is what I use. The cable box's HDMI out goes to the switcher, then one output goes to the TV (for video) and another to the DAC. It looks like your DAC lacks an HDMI input, but you could use an HDMI to USB convertor there.

So, what I am planning to do is purchase an Optical audio cable to run from the Opt output on the cablebox & then connect to the Opt input on the DAC. I can control the various inputs on the DAC such as USB and Opt from the front panel of the DAC. The Analog RCA ouputs on the DAC are connected to RCA inputs on the int amp. This way I can see for certain if it is possible to configure a new power amp in the future this way , since the power amps I am looking at all have just one set of RCA inputs as opposed to int amp with several. The results will determine if a new power amp is the way to go and indeed possible or will the new amp be an int amp affair. I will report back on what transpires over the next several days. 

Sure. Just run the analog outs through an ADC. After running it through an iso transformer to cancel the hum from cable’s non grounded ground. Why oh why? Every cable box I’ve ever had has one or more digital outs.

You’re going to have to understand the difference between analog and digital. No one else can do it for you.

So, I ran the new opt cable from the cable box to the DAC , which in turn is then connected via RCA cables to the int amp. Next, by switching between the input sources on the DAC , selecting the opt there , sound came through. Just so much lower in volume compared to the previous setup of RCA cables from the cable box to the DAC and onto the int amp. Although much lower in volume , the sound seems a tad warmer in tonality compared to before. Just seems a bother to set the amp volume for the cable box & TV sound so high , then when switching back to the USB input , the volume is quite considerably higher. In turn , requiring instant volume adjustment or risk waking the neighbors.