Good morning.
I have a pair of Gold Note Evo 6 speakers.
I want to buy a Naim amplifier.
Amp + power supply + preamp.
Or Supernait 3.
Can you give me some advice?
Book a demo with your nearest Naim dealer. Take your Gold Note speakers with you and demo as many Naim amp options as you can. Then chose what you think suits you and your speakers best, then book a home trail for your chosen amp option.
I have the same speakers, any modern Naim amp will easily drive them. I ran mine with a 282 with two hicaps and a 250dr, have since moved across to Chord pre and amp. Get some home demos of a few amps and try them.
Anything between a Nait 50 and Statements 
I’d compare a Supernait 3 and a 332/250 combo. The latter costs three times as much and only you will know if it’s worth the difference. If you are happy to buy used, a 282, Hicap, 250DR is probably the one to look at.