As far as my experience is concerned, you have three sensible options (I say sensible because there are people, in this world, who would keep the system and change the house): a), a power regenerator, like PSAudio or the like; b), accept that the thing is Naim-inherent and live with it; c) change brand.
Did you deliberately omit the option of a DC blocker?
Re b) accepting it is inherent when with Naim when bad mains is causing it doesn't make it acceptable in use if it is interfering with enjoyment of the music or the room!
And re c), it is important to be aware that it is not a phenomenon unique to Naim, and if the cause is a mains problem there is no guarantee that choosing another make will avoid a transformer hum, though very likely different brands will differ in their susceptibility,, and indeed different models (also very likely there will be variation within the Naim brand or possibly even between different examples of the same model).
As for moving home, that of course is a balance for the individual, as in how critically important to enjoyment of the home might be enjoyment of the music unfettered by annoying hum vs whatever other factors may be at play... but if someone has a loved but susceptible piece of kit, then take it with you when home hunting!