Multiple thankings to everyone who chipped in.
It’s been useful having an extra day to mull things over.
Tomorrow I intend to show the electrician the main diagram and ask him to use 6mm armoured cable to install two radial circuits ending in two pairs of unswitched sockets, earthed back to the main meter (separately earthed from everything else in the house).
Does the above make sense or have I misunderstood something again?
@Graeme how has your installation progressed? Spill the pulses.
I installed 2 unswitched double sockets on a single 10mm radial may years ago when such DIY was still legal. It was a pig of a job, but I got there eventually, so YES it’s doable.
I would also like to intervene in the 6mm vs 10mm suggestions;
My 10mm cable is only 5 meters long from CU to socket, and it replaced a 6mm one installed by an electrician friend some years earlier.
The difference in the sound of my system between the 2 was not small. In fact it took a few days of burning in, and aclimatisation for my ears, before I could decide if I had done the right thing. The change was that dramatic.
The Naim advice is a single 10mm radial and unswitched sockets and I for one have no reason to dispute this,
cheers,
Paul.
ps no idea why the format is stupid, but I failed to edit it back to normal several time before posting 
No!, please see my other post 
Use 10mm. Don’t spoil the ship.
Get more sockets than you need would be my advice…them PS’s can creep up on you!
Re the earthing, you can but lean on your sparks for their advice and testing on this. As some have said above, my understanding is that this will be influenced by existing earthing arrangements.
Many years ago (and perhaps still now?), it was preferable to have dedicated earthing for the hi-fi but I think earthing arrangements in modern-day houses may have changed.
At all costs, avoid potential earth loops.
Electrician testing the circuits now.
G
Was that loud bang emanating from Scotland?
Don’t joke. Sitting in the cold and dark as everything gets switched on, then off, then on…
G
Sorry!
Electrician counting his way round the board…
G
I ran a 10mm spur to unswitched MK sockets when I redid the floor, making sure the socket cabling ran well away from anything else likely to interfere with them. In my case they’re just on a separate circuit on the main Consumer Unit in off the mains. I did dabble with running a separate circuit off the main 100amp feed but in the end worked out that the resistance to ground was so low the benefits would probably not be worth the extra effort and cable runs as my meter is on a box on the outside of the house and I then have tails inside to the CU. The internal run is very short between the CU and sockets as well. I’ve not had any issues since it went in and however you do it, if you can and it’s not too complex, worth the effort to further refine the system performance overall.
Just bare in mind that the sockets are usually designed for smaller circumference twin and earth, 6mm will usually fit fine, 10mm is very stiff and depending on your Electricians willingness could involve a bit of swearing and wrestling to get the connections tight and the faceplate flush to the wall!
I ended up with the MK switchless medical type ones and they’ve been fine.
10mm it is, then. You may wring from me my slow consent.
I look forward to explaining all of this to the electrician tomorrow who already considers me to be several wetterflecks short of a sou’wester.
Might pritt-stick the circuit diagrams to the cat, lock them in a room together and feed whichever creature emerges first.
My fix still ongoing. He was very matter of fact about my request…no sideways glances!
G
The most challenging aspect of the installation will be connecting the T&E to the faceplate, some have better screw connectors than others inevitably so don’t scrimp on the socket selection!
Bare in mind 10mm T&E is typically used to feed things like induction hobs in kitchens not ring main 13 amp sockets!
I’d done cable runs and laid a new floor before that thought even crossed my mind so do check if you can that the faceplates are 10mm T&E friendly and you’ll have enough wriggle room to get the socket screwed in snug on the backbox, ideally match the backbox to the faceplate manufacturer to ensure enough space and a true fit.
If your schedule allows you can do a trial run with a short length off the drum to see how it looks when wired together, cable, faceplate and back box.
Expect some 4 letter words from the electrician trying to get it flush fit against the wall 
Good luck!
My first suggestion would be to sound out your electrician carefully. He may think you are being rather Quixotic, and will try to persuade you that all this stuff is pointless. He may even just nod when you tell him you want 10mm cable, and stick 2.5mm in anyway because it’s cheaper and easier, and he “knows” that it’s all you need. If he sounds like he’s not fully on board, I would find a different sparky.
Another point: how many sockets do you really need? Do you intend to expand your current system, which as far as I can see, only requires 2 sockets. If you don’t intend to add more boxes, 10mm cable into one double socket is simple, and you’re not faced with the issue of how to wire multiple sockets with fat wire that doesn’t fit.
Hi Chris. I’ll do four sockets. As you say I’m only blessed with two boxes currently but I harbour modest hopes to extend this tally over the span of my remaining years. Probably end up with whatever replaces the 272, a pair of throbbing 135s and a power supply of some description.
I’ll plug my overdraft into the standard ring main.
Here’s a funny thing. My 272 and 300 sounds considerably better when plugged into the block than directly into my double wall socket. No idea why, but it does. That’s why I think only a single double socket is required. Make sure it’s unswitched too.
As HH says, one double socket is still the preferred option for some people, perhaps with a decent mains block added later if you need it.
Night and day?
Changed my life. Better than a million power lines and inky blackness to die for.