I have a Panasonic Viera TV THX model, horrible sound. It is connected to a soundbar. I want to be able to listen to the tv with headphones. No jack from tv, I purchased a headohone amp/dac. Also have a cable box. I connected the headphones through the am, put want the sound only through the headphones and it comes through tv when I change the rca to amp (confuising sorry. Should I connect through the Cable box. Is there a a way to hook all this up and hear only through the headphones. I am hearing impaired and need to turn up the volume which is why I only want it through the headphones, but, be able to switch back to the sound bar when not listening through headphones. Trying to avoid buying receiver. Thank you