Switching Routine

I have a NAC152XS pre-amp powered by a Flatcap XS, which also powers a StagelineMM. All of this feeds into a NAP155XS. When I switch the units on I always get quite a thump in the speakers, so have found I tend to switch off at the mains only (and in turn change the on/off switches on each unit before switching back on). Whichever way I switch on seems to be the same, so is there a right or wrong sequence to follow i.e. Power Amp first and then Flatcap, or vice versa?

power amp on last, off first…

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In general the order is to switch off power amp first. Without the power amp no other switch-off transients can be amplified into the speakers.

Conversely with switch on, the power amp comes last, so it doesn’t amplify the switch-on transients of any of the other components.

Switch off. …Power amp, pre-amp, the rest
Switch on…the rest, pre-amp, power amp.

It sounds from the original post that you are switching them on and off frequently. It’s much better to leave them switched on all the time unless you are going away for a few days. That way you will get better sound and no switch-on thump.

That’s a good point…is it better to leave the units on? The retailer told me it was better but to me it uses energy and shortens the life of the products. Is there any evidence to the contrary?

Clearly it uses energy but it won’t shorten the life. Electrical things are most likely to fail on switch on. You can save the energy by replacing all your lights with led and turning down the heating, etc etc.

Does anyone have an idea of how much energy? I get that the highest risk is at switch on.

…this from a man that has Philips Hue throughout and Nest!

Look on the website at the specifications and you can work it out.

Easier said than done.

a) Are the ratings nominal, for example the power amp will use less with no load.
b) Does a preamp use the same regardless of signal transfer.

Clearly I am not an electrical engineer!

Many thanks

No idea. I wouldn’t worry about it. Just leave it on and pay the leccy bill. Turn a few lights off and wear a woolly jumper when it’s chilly and all will be well.


Definitely look into getting those switched mains sockets for unswitched. Switch switched for unswitched.

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