I've never found anything immune to a power cable unless maybe it has no safety ground, then it might be close.
Do you use large chokes in your devices? I've never had the chance to hear SAS in person.
Good questions for the general public as well.
The power cord pin 1, safety ground, is the main culprit when using two components, say preamp and
amplifier together in a system.
I found my old block schematic I hope makes it simple.
Red inside each component box is signal ground for both, or more channels.
Each ic cable has inside and a shield. Signal return is via the shield of each channel, and some mixing
between the channels along the way.
Notice the pin 1 ground wire of power cords are connected via the outlet and to the signal grounds of each
component.
(Actual ground means nothing, just the fact that both pin 1s of the power cords are connected at the
outlet.)
Each center conductor is exclusive in its channel musical signal. Return, however, has three conductors, shield,
shield, and pin 1 ground wire. The ratio of signal current is frequency dependent upon the DC resistance,
inductance and maybe capacitance of each return path.
As far as chokes/inductors, chokes are used in single ended circuits such as SETs, Preamplifiers,
and Phono stages etc. Due to their enhanced ability to reduce hum. In push pull circuits the
120hz ripple is basically cancelled.
The disadvantage of chokes is that when connected to a power supply filtering setup, there are three
reactive circuits together next to the signal tube, capacitor, inductive, capacitor. (With inductive input, we
have inductor, capacitor and is a little better, but not much.)
Cap C1/inductive/cap C2 is especially complex
and a non linear problem. (I know, a basic few say "passive" caps and inductors are linear. But the
results of use demonstrate they are not. Any sonic difference cause by said "passive" parts is a form of
distortion.)
The inductive reactance of a choke is calculated as: 2pi X F x L
where F is frequency
L is inductance
pi -3.1416
x is times
Notice the inductive reactance is frequency sensitive. The isolation between the two capacitors C1 and C2
is via the choke's inductive reactance. So that schematic showing C1 and C2 looks nice, but is far from
true. C1 and C2 are not really just C1 and C2.
Now add the DC resistance of the choke's wire, which is constant over the audio band, and we
have something even more nonlinear as shown by the photo below.
If we use a straight non inductive resistor, essentially has the same resistance over the entire audio band,
the isolation of C1 from C2 is constant over the entire audio band.
I use no chokes in any of my electronic components. The speakers, I use 2 very low resistance chokes in the
crossover for a quasi second order configuration.
Hope this helps all.
steve