I find this subject interesting, but it always remains unresolved, so I’ll attempt to summarise. The Naim rectification scheme is unusual as it involves using two centre-tapped windings on the one transformer (see post #1). It provides either (1) a single +V/0V/-V output to a power-amp, or (2) two +V/0V outputs to (say) a Hicap. You could vary that scheme of course e.g. four centre taps to double the number of outputs, the windings could be on different transformers, or a single centre-tap could produce a single +V/0V supply. EDIT: This is classed as full wave rectification.
I remember asking Naim why they did this, and was told bluntly “it’s a secret”. Various comments on this thread seem to imply that Naim didn’t know what they were doing. Martin Clark’s plausible answer is that it makes no difference, but only in so far as it doesn’t “waste” half the power of the transformer. A few people do say it’s better sounding, but they’re rather unusual and it’s obviously more expensive to implement. In consequence, I wrote it off as unimportant, long ago.
As with many things hi-fi, any advantage (probably) cannot be measured and therefore it’s unproven. If it reduces noise though, which seems likely, then that could be measured. It’s a matter therefore of believing someone else’s ears before deciding to build. As a result of this thread, I’m now prepared to try it next time I do. Whether I try doing an A/B comparison is another matter.