Pass XA 100.5 plugged into Power Plant Premier?

they will sound better straight off the wall

Depends on how loudly you play music, and if you like the change in sound the conditioner/regenerator makes.
The consensus is amps off power conditioners. because they limit various parameter of the sound.
I use a Furman Ref 20i to run my (small) Forte 4a or soon to be mine Bryston 4B-SST*2
I use the conditioner because it gives a slight increase in PRAT and warmth my system needs.
I love clarity, and my choice of electronics leads to a slightly thin sound. the Furman 'fixes' that and still leaves the clarity.
On the other hand if you play at substantial volumes the PPP may run out of power and be much worse than the wall.
When the PPP fans are screaming and it is still really hot to he touch you know your pushing it.
On the other hand the guy I bought the Furman from had his giant Pass monoblocks plugged into it.
I use a PPP just for the preamp.
(I am becoming a power conditioner nutcase!!)
But can say, conditioners change the sound in subtle ways.
Just do you want that?

Electrical norm says that the voltage maximum deviation should not exceed +5V or -10V, so everything between 198V and 232V is still within the specs.

You will be fine running your Pass from 210V mains on 220V setting. It may be short of 5W of its maximum power, but that's it.