Best means of isolating digital equipment i.e. DACs, CD transports, wall warts etc.

Eric, you have to be careful with Parts Connexion. They can be a terrible rip off. They sell 14 gauge three conductor shielded power cable for $100/linear foot. But here is basically the same stuff for $3.00/linear foot
https://www.wireandcableyourway.com/belden-9367-14-awg-1-triad-shielded-300v-power-limited-tray-cabl...
You can make a wonderful shielded power cord for $45.00 and make them to fit perfectly. 
If your power is reasonably clean all you need is shielded power cord not only to keep stuff out but to keep stuff in, isolating your interconnects from the power cord. 

In reality there is no such thing as a dedicated line. It all goes back to the same panel and mains. The individual lines are sized to the circuit breakers. Very few system in their entirety are going to trip a 20 amp breaker. Adding more current capability may make you feel better but it will not improve the sound in any way. As far as noise is concerned all the stuff in the house is connected to that panel. So, see if any of it causes noise. Turn your system all the way up and turn an the AC. Stick your head in the speaker. Do you hear it? Next the refrigerator. Turn down the thermostat. Do you hear it in the speaker? What about the washing machine or the blender. If you have good components you will not hear a darn thing and if you do not hear a darn thing forget about it. You do not have a problem so stop wasting money on a problem you do not have.