Should Amps be plugged into a power conditioner?

Should they is a judgement call and I encourage you to test with your ears.

I have a Shunyata Delta power conditioner and plug my Moon 860AV2 into it.  I like the sound and I also appreciate the protection.  (I also have a whole house surge protector.)

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.

My power spikes minimum 3 x a wk.ihave to use them and have several types most high end.i might lose some sound quality but not 30 k worth a Mac 1.25 and several others even through the surge protectors. The emotiva amps go into safety mode even though high end surge protectors and sound conditioners.they have some type of protection from factory.other amps dont.i have several amps that are 20 amp high watage sometimes 1 amp 1 plug all on 20 amp lines because sound cond only do so many amps. I wish I could plug directly in to the wall but can't risk it.most manufactures state plug directly to wall. Sometimes it's a compromise. Enjoy the music.stay healthy.music calms the savage beast.

Luv the atmosphere comments and his knowledge has always seemed more valuable and correct to me wish more manufacture would comment without bias like he has done 

I've used power conditioners for a long time from an Adcom ACE 515 (still in my video system) to my current Bryston BIT-15. I always plug the power amp into the outlets designed for them as I like a single switch that turns the entire system on...power amp last on and first off using the amp's switch (the Bryston doesn't have the ability to do this itself). No hum, everything dynamic as it should be with zero difference between plugging the power amp into the wall or the conditioner (yeah, I checked that out). I use one of the "garden hose" Pangea AC cables for the Bryston.