Doh 
XPS’s are known to be, shall we say, a little marginal or picky, regarding their fuses. Best left powered up, to minimise problems.
Why did the fuse blow…? Inrush Current & Cycles.
There is actually a lot of science behind fuses. Although fundementally it is just basic mechanical engineering.
The in rush current is the likely culprit. Combination of large inductive load charging those caps. Fuses also suffer from cyclic stress, fatigue. So will fail at a lower current after a number of cycles compared to when new.
However I expect the OP has failed brand new fuses. The 2.5 A fuses are marginal looking at other posts. With the next size up 3.15A a no no. As to why some xpsdrs eat fuses and some don’t, might be down to local supply voltage. Assuming each xps is identical.
3 Likes
Some power cables like Wireworld have lousy fit on the IEC and the slightest movement or touching them cause fuses to blow. Make sure the power cable used fits great. It is a big difference between brands. Best fit I’ve tried has Audioquest. Better than Naim PL and original.
I’ve had XPS2 from new for about 8 years now and yes constantly switching on off does stress the fuse. I’ve had one shatter big time that was through not leaving off for at least a minute.
Always leave on apart from usual going away etc. Also being hesitant when pushing button can have same effect. Summing up stop messing with it and leave on
Agree a tentative turn on does seem to encourage the fuse to blow. A quick assertive prod works best.
I just leave mine on these days.
2 Likes
It’s been a while since I had my XPS2 but I don’t recall it ever blowing a fuse when cycling on/off. Weird. Perhaps the mains voltage/amps here in the states act a little differently.
Quick update. I received the fuses as specified by Naim today and tried one. Although it didn’t explode, it did blow on turn on so can only presume there is something more at play here than just the usual inrush current fragility.
It’s going to the dealer for a look and if that doesn’t resolve the issue it will need to head back to Naim for a proper investigation 
Can confirm that the power cord is seated correctly and there was no pussy footing around with the power button activation!
I had a PS fuse blow on switch-on over the weekend - I think as the Powerline didn’t seat 100%. Who knows. And the elderly fuse exploded likewise - all good now.
Have you checked the plug socket end of the cable too (opened it up)/used another cable?
I would try one more, and if that blows then it may well indicate that there’s a problem - after all, the equipment fuse is there to prevent serious internal meltdown should a fault occur.
1 Like
Have you checked your supply voltage?
Can you change the power cord, and the socket it is connected to, and try that before going further ?
I have a brand new powerline lite spare so will hook that up to a different mains outlet this evening and try one more time just in case there is a cable issue - unlikely but possible I guess.
My dealer has said he can collect next week and if confirmed there is an issue it will go back to Naim.
How does the warranty system work? It’s a second hand unit but only 3 years old so will I be covered under the 5 years warranty, or will I have to stump up repair costs if there are any?
1 Like
Good luck! Make sure the IEC plug is tight like Slamdam said above. The only time I had the fuse blow was when I had inserted the Powerline sloppily. I touched the cable, it moved in the plug and sparked, and the fuse went off. Never happened with properly inserted PLs
It’s probably a capacitor going bad if it keeps blowing. Or less likely, could be the primary windings on the transformer are shorted.
I would try another fuse if at all possible, once working as it should one can almost feel the trousers flapping from the energy of the force! 
One last trick I have done before is … switch off un plug leave few minutes. Put power switch on Then plug into wall socket or if using switched sockets switch on. If fuse blows then I would be returning to dealer. Just a last thought