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

I wouldn’t. It could restrict the power to the input of the Power Plant Premier. If anything just use a good 5ft or 6ft audiophile grade power cord. Minimum 12awg conductors. (Borrow for a listen before you buy, if possible)

How tight are the wall receptacle outlet electrical contacts. Does the plug fit snug or loosely in the outlet? If the receptacle contacts have lost their contact memory retention to male plug blade contact pressure you might want to hire an electrician to install a new outlet. (Poor contact pressure can cause series micro arcing when a load is connected. Series micro arcing causes AC Line harmonic distortion.

I doubt the Landlord/Building Manager would have a problem with that. You could always give him/her a call for permission. He/her may say yes, but you will have to hire the electrical contractor/electrician he/she uses.

All you need is a good heavy duty spec grade duplex receptacle outlet. The electrical contractor/electrician, if the electrician knows the electrical safety code(s), by Code he/she can only install a UL Listed duplex receptacle. If the circuit that feeds the outlet is 15 amp then he/she per Code must install a 15 amp duplex receptacle.

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.