Personally, I wouldn't take either for Naim. I own the Supernait 2 and have found that there's only a handful of speakers that have great synergy with Naim. And I've found the result to be sometimes contradicting to what I've read.
The Nait series, including the Supernait 2, doesn't have great power. They give the elusion of great power. My amplifier turned out to be just enough for the speakers I'm using. If you are using the 5si, you will find that its bass is quite strong. People think it's punchy and rhythmic. But so is the Dynaudio X12. This speaker's characteristics are almost exactly in line with that of the 5si, with a reticent treble. On top of that the X12's are not easy to drive. When Dynaudio moved on from the Audience series they kept emphasizing the "more efficient" part of their specification. It's true that they are easier to drive than the previous models, but essentially it's not the easiest speaker to get the best out of. Dynaudio loves Simaudio. They just complement each other so well. You should check out the power that a 50w Simaudio could pack.
Focal Aria works quite well with Naim. It's still not the most synergistic match despite the fact that both brands are under the same roof, so to speak, but Focal Aria and Naim can be very enjoyable.
Lastly, don't put the best value for money products together and expect it to sound amazing. If you haven't gone through the long and arduous process of auditioning and making mistakes, it's very difficult to create the sound of your dreams. Speaker cables and power cords are fun to mess with, because they make things sound different, not necessarily better. Hoping to "fix problems" with cabling is the truest sign that you are not happy with what you have.
Hope this helps somewhat.