I've never owned a Naim product, but I've heard a number of them ever since I was loaned an early NAC 12 and NAP 250. I think they were the numbers - a preamp with phono board and the original power amp. Probably made by Mr Vereker himself. Had terrible switch on thump, was sensitive to electrical switches around the house, hissed quite a lot, but sounded lively and enjoyable.
They still sound lively, and the PRAT thing was the way it was marketed. I get the idea, but since my references tend to be orchestras, singers and pianos, comparing obscure pop tracks wasn't my bag! From an engineering angle, I gather they use an inductor in the output stage that reduces the damping factor. That may give a 'boppy' bass, but I'd always thought low output impedance was worth striving for.
A few years ago I attended a Naim roadshow with the quite new streaming products and a new DAC. I'd almost convinced myself streaming and hi-def was the future, and their NDX seemed great and almost affordable. It sounded fine too. Then they plugged in the standalone DAC, in lieu of the built in one. It sounded much better. That did it for me: I'd be permanently dissatisfied! There would always be another few grand required to upgrade.
I still don't get why they need servicing regularly and I suspect it's about profits not good design or specs. But they are British and the backup support is great. Not for me though.