The speakers you have chosen are rather demanding, particularly for an ‘all in one box’.
Although a Nova CAN drive them you’re going to have to arrange things to give it every chance of doing so properly, you need to optimise all the service conditions to be as ideal for the Nova as you can achieve; this means:
Get the Nova switched over to 110V (rather than having its power supply hampered by an additional transformer).
Use at least 3m of NAC A5 speaker cable each side (and 4m or 5m would be better).
Plug it directly into the wall using a Powerline (N.B. don’t use an extension cable).
Position the Nova so that there’s free airflow around it.
It will probably also be of benefit to put the Nova on a properly constituted HiFi rack.
I highly suspect these are a major issue here - twisted/braided cables are not a good partner for Naim, and can contribute towards overheating issues (as several people on these Forums have experienced.)
Uniti is more forgiving than some earlier designs, but i’d still recommend 3m+ pair of cables - non-twisted; non-braided. As noted above, Naim’s own NAC A5 would be great place to start.
Is this speaker cable intended for car audio use? Focal are big in car audio and I’m not aware of them supplying any domestic HiFi speaker cable. Maybe worth checking the spec?
My guess is that there are other factors at play, but this could still be a contributing factor.
They also supply home cinema solutions, pretty big ones, and I think that they might also have cable for this, in addition to cars. But there’s scarcely any info on focal.com. In any case, as the cable used is only 1.5 meters on one side it would have to be pretty special to provide the same values as 3+ meters of NACA5, and it most likely isn’t