Would it make sense and be safe to put power conditioner in front of PS Audio regenerator?

No. the PP rectifies the input AC and starts all over inverting it. anything you do upstream can only hurt. traditional power conditioners have a nasty habit of limiting current.

a dedicated line does almost nothing to improve the quality of the power--it ensures that you have adequate current. It also ensures you don’t have something else plugged into the circuit that causes noise. you can manage this yourself by figuring out what other outlets are on the same circuit and either moving things to other circuits or making sure noisey appliances are off or unplugged while you are listening.

Jerry

a dedicated line does almost nothing to improve the quality of the power--it ensures that you have adequate current.

Strongly disagree... Depending on the wiring method(s) used for the in and out branch circuit wiring connections at every wall outlet box plus ceiling lighting outlet boxes of a convenience outlet branch circuit a dedicated branch circuit can make a big difference.

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@jea48 and @carlsbad2   -  I agree.  Straight from the wall to the PP.  12 awg or heavier power cord with solid plugs on both end from the wall.  It doesn't need to be a very expensive one because the key thing is to get the needed current to the PP.  And as @jea48 mentions, a worn out, light weight, loose receptacle should be replaced.

Not in front of–but you could try beside. Use one for the source, the other for the amps. Use same twin outlet. Also try direct to the receptacle with no conditioners. 

I see. I won’t do it. I use Purist Audio power cord from the wall to the PS Audio Premier and the connection is tight.

Without the regenerator it is incomparably worse, everything should be plugged in it.