Well, where to begin with this one? I started out with Naim very early 80's with a couple "chrome bumper" pieces, but really enjoyed the switch as the "olive" line came around. I started the olive series with a Nait2, Nat02 tuner and the CDI when it first came out. This eventually morphed into an all-active CDS2/82/Nap-250 pair with Naim SBL's and all the power supplies etc. And now, to the newer, but yes "lower-end" stuff, the Uniti/Nap-100.
If I was to try and make it simple, I would say to my own ears that the early gear including the olive range, had a more bouncy/funky way it just seemed to groove, don't know why or how to explain that. Yes, PRAT and all that. I also felt the frequency extremes were somewhat rolled off, but ultimately, it was just fun to listen to, especially when a pair of Linn Kans or SBL's were on the end of it, but a lot of other speakers worked too, such as Rega and Rogers.
Where I think the new range has gone is it just seems a bit smoother now across the frequencies and not as rolled off at the extremes, although I still think it is very slightly still compared to other gear-but which is right? I also believe their gear now works with a wider variety of speakers than it might have used to. Either way, I have always loved Naim for many reasons, their service and spare parts is extremely good, they take very good care of their customers. Build quality and general longevity of a model is fairly long term in the audio world today. But most of all, I just love the music they make. Not cheap by any means, but very solid and a good investment long term.
With that said, I do not typically get along with their speakers like I do their electronics. My active SBL's were quite a challenge indeed to get setup and sound right, but when on, a very good little speaker, and run active, in another league from passive. FWIW, not much really.....Tim