Should Amps be plugged into a power conditioner?

@dentdog Anything with a transformer (like an isolation transformer) is subject to the distortion made by the transformer itself. Generally speaking, to avoid excess distortion from the transformer it must not be loaded past 50% of its rated capacity. You'll have to work out the math (Firefox has a security warning on my machine that suggests the Audiopax site doesn't have a proper certificate so I couldn't make out how much current the amps draw) to see how you sit. Obviously a passive power transformer cannot correct for a line Voltage drop and it will pass distortion that is already on the line.

@immatthewj Power cords (and power strips) have a Voltage drop across them (Ohm's Law), which is why power cords and the like have an effect on the sound of the equipment used with them. You really want to keep that to a minimum. The more power the equipment draws the more effect the power cord can have; feedback in the equipment will help it reject AC line Voltage effects. So the efficacy of power cords and such vary from system to system, sometimes by quite a lot.

I use a power strip in my system but the amps are not plugged into it- they run off of AC lines of which they are the sole user. My preamp is pretty heavily regulated so it tends to be immune to power cords and the like and the rest of the system hardly draws any current, so it works pretty well. 

Current limiting starts at the power cord. Any time you have a glorified power strip, like so many so-called 'power conditioners' seen marketed to the high end audio community, the power cord it uses will have a voltage drop.

We recommend to our customers that unless they have a real power conditioner (like the old Elgars, or possibly one or a pair of the higher powered PS Audio units) that they plug directly into the wall. This is not only because of the sole power cord issue I just mentioned but also because most of the 'power conditioners' we've seen don't do much at all or can have deleterious effect.

The guy doing the teardown at the link doesn't understand how the Elgar works and these date from the 1970s not the 1990s :) so they usually need refurbishment to be reliable (they are designed for 24/7 operation). Elgar got out of the conditioner market in the early 1980s. 

The Elgar is a good example how how power conditioning should be done. It has an enormous power transformer through which the AC line moves. It has taps for various power supplies for the low distortion oscillator, housekeeping circuits and the large feedback amplifier. The output of the transformer is compared to the oscillator which is sync'ed to the AC line frequency. The feedback signal thus generated is amplified and applied to the transformer, bucking its Voltage (IOW 'regulating') and correcting distortion; this is done without current limiting right to the upper limit of the unit's spec- in the case of the one at the link, about 30Amps!

The PS Audio Regenerators also use an oscillator and an amplifier, whose output is converted to the AC line voltage by a transformer. Feedback allows it to also maintain low distortion.

If your conditioner does not do these things its likely so much junk. It might help in low current applications for isolation (such as seen in the Furman units) where power amplifiers should not be involved. If you don't have active circuitry to allow the conditioner to maintain low distortion of the output AC waveform, its not really going to work. You may have had good results with whatever you're using, but if you have a real conditioner the results are far more palpable.