It seems a common trend on forums recently to shoot down anyone who even dares to ask a question about the mains supply. Seems a lot of forum members suffer from either 'fear by proxy' of someone else getting hurt, or the delusion that nobody other than them realises that mains voltage is dangerous. Domestic electricians are not automatically going to know about hifi, and hifi aficionados are not automatically going to be qualified electricians. However it's not uncommon to have dedicated supplies fitted for high end audio systems, and the biggest hifi forum on the web is probably as good a place as any to start asking questions about such a setup.
My first step if tackling something such as this would be to check the AC supply for DC offset, fluctuations, noise created by other equipment in the house etc.
It may not need a dedicated supply at all, or an Isotek (currently under £300 on an auction site) might fulfill the job. Having said that, if your neighbour has spent £50k+ on a system he probably wants to continue throwing money at it for 'peace of mind'.
I write this from experience, having considered a dedicated spur for my system, before measuring the supply and finding it already pretty damn clean as the only thing running in my house when I'm sat in front of the hifi is a fridge and a laptop. I also think that the install you suggested, if required at all, would be a good choice to isolate the audio system from noise generated by other electrical gear in the house. It's not going to clean up a dirty mains supply however.
I have yet to see a consumer unit with silver plated contacts, but a visit to your local electro-platers would sort that out if you were handy enough to take the thing apart and reassemble it. I would however not advise doing that as the potential risk (fire & lack of insurance cover) far outweighs any possible gain. There is more to be gained from a mains conditioner of some type, a dedicated ring would only come into it's own if the power requirements of other equipment pushed the total load toward the 30A limit.