Replacing generic RECEPTACLES

Testing for same leg:   
"" Say you have two lines running to the stereo equipment area.
Say line A and line B    
Line A duplex The hot is the narrow slot (if the ground is on the bottom, the right slot)     
Within a single duplex:       
The neutral is the wide. or left slot     
AC voltmeter prongs in narrow and wide reads around* 120V   
AC voltmeter prongs in narrow and ground will also read 120V    
AC voltmeter prongs in wide and ground will read 0V    
(if you readings within a single duplex are different, the duplex is wired WRONG.)       

Same if you go to just line B duplex. same results within line B duplex

However to test if line A and line B are on same or different legs.    
AC voltmeter prongs in narrow slot of line A (Hot)     
AC voltmeter other prong in narrow slot of line B (Hot)    
If this reading is 240 volts, you are using both legs.    
If it is zero 0V then you are using the SAME leg and are safe.   

To just mention (but these do not matter to the test) other connections.   
If you connect the AC voltmeter from line A wide slot to line B wide slot the reading will also be 0V no matter if one leg or both legs.
If you connect line A wide slot to line B narrow slot 120V no matter if one leg or both legs. Line A ground to line B narrow will be 120V
Same thing line B wide slot to line A narrow slot 120V no matter if both legs or one leg. Line B narrow slot to line A ground will be 120V

* the voltage may be near 120V it may be 115V or may be 125V, but it will be close.   
Same thing wit the 240V reading, it may be somewhat off, but still near 240, 230 243 etc.    

@elizabeth ...... Elizabeth  Thank you for the last 2 replies to me.  I still really dont understand what you are talking about. And i appreciate your time writing all that. I will have my electrician in stall a 20A dedicated line for my Furutech GTX-d r for my CDP so i know for sure there is nothing else on that line. also that way if and when do buy a Shunyata power conditioner for my CDP i can use the 20A line too. 

The Furutech GTX -d Rhodium is the best duplex you can get and to complement it, install the Furutech FI-09 Rhodium IEC on your equipment. BIG improvement especially for the cost of admission.

tecnik........ I can not do the Furutech FI-09 Rhodium IECs as i am using Shunyata King Cobra and Sigmas. 

Not sure i know what you mean by needs to be on the same leg of the service panel as my 20A dedicated line, same phase. And what do you mean by appliances? blender ? microwave? toaster? Im not trying to be funny but i have a dedicated listening room. Its not in my kitchen.

The wiring in a residence is called split-phase and is divided into 2 legs. On the service panel you will see Leg A and Leg B. The goal in the panel is to even out the load, half the current draw on A and half on B. If you wire a refrigerator on A, then a second high current appliance such as air conditioning should be wired to B.

Simply put, In an audio system, we want all the components on the same leg so there is minimal noise from other devices wired into the panel. 
And yes, I am talking about toaster, blender, refrigerator; all adding noise and interference down the AC line and contaminating the other circuits.
Electricians are only concerned with balancing the current draw in the house, so roughly half from Leg A and half from Leg B. And they commonly will daisy chain several AC outlets onto the same breaker. The kitchen toaster outlet may be combined with the lights in your living room.

If some of your audio system is wired to A and some to B, there is more risk of noise from the circuits in the other leg of the panel getting into your audio lines.

A test for a shared line is to turn off the breaker to your CDP and see what other outlets in your house lose power.

https://diy.stackexchange.com/questions/13105/are-both-legs-of-a-homes-power-supply-equally-used