When a high inrush current device keeps tripping a circuit breaker it’s worth getting an electrician to check things out as it can sometimes be indicative of a fault somewhere in your house wiring. Of course, it may just need a different circuit breaker, as already suggested, but again, it’s something to ask your electrician.
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DEFINITELY the type of circuit breaker in use. It needs changing on the consumer unit.
My XPS used to trip out the circuit breaker nearly every time I turned on the XPS.
It continued right up until the type of breaker was swapped (by my electrician) to one with different properties. This is due to the large initial current draw when the XPS (and other large items such as power amps and other power supplies) turn on.
The one I now have installed in the consumer unit is a Type C, 20 amp, on a dedicated supply to my system.
The difference is that Type B devices are designed to trip at fault currents of 3-5 times rated current. For example a 10A device will trip at 30-50A. Type C devices are designed to trip at 5-10 times In (50-100A for a 10A device).
*** I am in the UK and other countries may vary **
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Thanks. I will get in touch with my electrician. You also suggest the XPS is not the issue, right?
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Lots of people have this issue, so it’s highly unlikely to be the XPS at fault. To save the cost of the electrician it’s well worth buying and fitting a Type C breaker with the same amp rating as you have now. This has been mentioned several times above. Look at your current breaker and see what it says- it very likely is a B. Swapping them over is perfectly safe and takes seconds. But of course, if you don’t feel confident in doing it, the electrician can do it for you.
I don‘t feel confident 
Probably easier to change the CB, than fitting a Naim Burndy… 
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There’s something a lot simpler than changing the circuit breaker that might be worth a try.
If you have a wall socket in the kitchen that is connected to an electric cooker breaker: power the xps from that socket for an hour or so, to get it nice and warm. Then quickly move it to your rack and plug it in.
Warming the capacitors up will reduce the leakage current, which may be the problem. New or cold capacitors have higher leakage current than run-in or warm capacitors. (Although 20 year old warm capacitor will probably have a high leakage current 
).
Can the OP confirm when this XPS was last serviced…?
It has been produced 2021. It‘s an XPS DR
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It is the breaker as others have said. I look after the maintenance of a large scientific building, we have lots big microscopes, centrifuges etc. These often have the same issue even when the amperage ratings are within parameter of the breaker. Most of these manufacturers will specify the breaker needed (but not always) type C, Type D etc. Change the breaker and enjoy your music!
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It is not just Naim power supplies, but common to equipment containing high current capability transformers, whether stand-alone power supply, power amp, or anything else. The answer is a suitably rated slow blow fuse (which I guess is what Naim’s internal fuses are). Ditto the plug fuse, though being there to protect the cable that might be resolved with a higher current fuse, depending on the cable rating. Normal domestic use circuit breakers in the consumer unit (type B) react rapidly, IIRC significantly faster than a conventional fuse of the same rating, which is where the problem may lie. A type C circuit breaker equivalent to a slow-blow fuse, intended for situations precisely like this, with high initial surge current. (There is also an even higher surge current capable version, type D, but that is extreme and usually only used industrially.)
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Just leave it on - problem solved…
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If they always trip the breaker how do you ever get them started 
The OP said it happens sometimes.
If the unit is not faulty and it’s just the common cause of fast-triggering circuit breakers, it typically only happens when you are unlucky to hit the power button at a certain point of the AC cycle where the inrush is largest.
If it happens every time, there’s probably something else that’s wrong
Once the unit is on, there is no problem. I can turn it off and on again. If I leave it off for about 5 or 10 minutes, then the circuit breaker comes into play…so I guess it is the initial high current causing this problem. Will have an electrician look at it, for now I just keep the unit switched on, which presumably is indicated anyway. BTW: circuit breaker is a B-type, so I will have a C-type fitted.
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That’s because the unit is warmed up.
Have you tried as I suggested yesterday, plug it into a circuit with a high rated breaker. (Cooker). Get it warmed up, then plug it into the circuit you use for your hifi, while it is still warm.
You don’t need an electrician to do that.
No, since I don‘t have a high rated breaker to plug it in. Obiously once warmed up there is no problem at all. I could leave it as it is, but I guess I prefer a solution where I can turn the device on and off anytime.
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If you didn’t know it before, no doubt by now you are aware of Naim’s advice to leave their power supplies turned on. This is particularly true of the XPS due to it’s sensitivity, which for many people tends to cause it’s internal fuse to blow rather than tripping the breaker. A Type C breaker should resolve that issue, but repeated turning on and off is not ideal.
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Maybe you have already responded on that, but why do you bother to switch it off? My 555 dr is on 24/24, as for the most Naim owners. I switch it off only if there are serious thunderstorms or if I am away for several days.
I have no problem in leaving it on 24/7 and I will do so. So, essentially it is not a real problem, but I would like to be able to switch it on and off at any time. That‘s what other devices can do as well…