Since the action of conditioning the power must consume some of it, the conditioners of which you speak presumably have power supplies of their own to make good the loss.
@clearthinker
They do.
The PS Audio, if I understand correctly, employs a low distortion oscillator that gets amplified by the power amp inside and then drives a power transformer. To keep the power draw of the device down they are probably using a control transformer for this task.
In the Elgar, there is also a low distortion 60Hz oscillator. It is synchronously locked to the AC line. The AC power goes through an enormous isolation transformer. This transformer has a set of windings for the power supply of the built-in power amp. The main output of the transformer is compared to the oscillator. A difference voltage is thus created and amplified by the power amp. The output of the power amp is applied to a feedback winding on the transformer. In this way the output of the unit is kept low distortion (no harmonics, especially the 5th which is the most problematic). The output voltage of the power amplifier is also used to 'buck' the isolation transformer, providing boost or decrease as needed. In this way its also able to regulate the line voltage without current limiting. Pretty cool!
In both cases the active circuitry draws power of its own. Care is taken to minimize the power draw; regardlesst does not rob voltage from the output in either case.
We used a PSAudio 20Amp unit at AXPONA last year. The hotel line voltage got down to 110V or less at times but our voltage in our room was always at exactly 120V.