On Wed, 5 Aug 2020 18:13:03 +0100, Bert Coules wrote:

It's not great on the mains side capacitors and rectifiers...a bit
of
inductance in series will help.

Thanks. Or presumably I could go with my original idea and put the
operational switch after the PSU, leaving that switched on for a whole
session.

Or dig abput in the SMPSU and see if the control chip has an "enable"
input that turns it on/off without having to switch the DC. Some
SMPSU's have poor regulation when they don't have suffcient load.

--
Cheers
Dave.