I would like to hook my satellite box to my oppo udp-205 for two channel audio

My understanding is that digital coax will be cleaner because optical is not really recommended for long runs unless your run is about as straight as a ruler.

Bill

I use coax from my UDP-205. This one specifically, but of course there are many coax options. https://www.bluejeanscable.com/pages/technicaldocs/1694tech.htm

Coax will sound better than optical.

But, you may experience ground loop hum problems using the coax cable.

What may cause the ground loop is any appreciable differences in lengths between the safety equipment grounding conductor of the branch circuit feeding the wall receptacle outlet the SAT box is plugged into, and the safety equipment grounding conductor of the wall receptacle your audio equipment is plugged into. If a difference of potential, voltage, exists between the two grounds there is a good chance you will hear a 60Hz ground loop hum through the speakers of the audio system. (Providing the SAT receiver box uses a 3 wire cord and plug, that uses the safety equipment ground, and any piece of the audio equipment, (Connected together by wire interconnects), the Coax cable will be connected to that uses a 3 wire cord and plug, safety equipment ground.)

Another problem that may cause a ground loop with using the coax cable is how did the installer of the SAT Dish earth ground the dish and LMB of the dish. How did he connect the grounding block of the SAT dish and LMB to the main grounding system of the electrical service of the house.

Any difference of potential, voltage, between the coax shield of the cable of the SAT system and any piece of associated audio equipment, that will be connected to the SAT coax cable, that uses the wall receptacle outlet safety equipment ground, will cause a ground loop hum. (They will be connected together electrically)

With optical there is not an electrical connection between the SAT system earth ground and the audio system equipment ground, if used.

You could start out by buying a cheap 30ft digital coax cable and see if you hear any 60Hz hum through your speakers. If no hum buy a better digital coax cable.

What about cable rg59,,,, 2 /30 ft runs and adapters to rca male plugs