Matching speakers to sstem.

I’ve just bought a name unity nova and i want to match them with sonus faber 4 ohms speakers will this combination work well considering the nova is rated 8ohms

Welcome to Naim Pheonix1, and welcome to the forum.

Naim normally only give the 8 ohm rating, that does not mean it does not have or is unsuitable for other ohm loading.

Stereophile (magazine) tested it & give the folllowing ….
Specified as delivering 80Wpc into 8 ohms (19dBW) and 155Wpc into 4 ohms (18.9dBW), the Uniti Nova delivered (in the Stereophile test lab) 103Wpc into 8 ohms at clipping (1% THD+N) with both channels driven (20.1dBW), and 160Wpc into 4 ohms (19dBW).

It depends more on which particular sf speaker you are planning to use. The ohm resistance won’t really tell you much about how a speaker will react to any amplifier. It can be a sign of a difficult load, but that (mostly) applies to esoteric or speakers not necessarily main-stream offerings. Either way , the power rating is usually a better way to at least consider if a speaker will work with the unity nova or not. A better (basic) determining factor is where you plan to locate the speakers ? - some speakers are better near a wall and others out into the room.