----- Original Message -----

My main
driver for using a 340V rail was the need to not have to have a separate
PA.  A 50V 25A PSU is fine if you can get one - I have an old telephone
exchange PSU - but normally it is a big beast if you have to make one
up, so multiple bridged lower voltage PAs is a complex way to go if
building from scratch, even if a lot safer.

If rectified mains power supplies are to be considered, one way to improve
safety is to use a 1:1 isolating transformer, which are fairly available.
It should at least be used for doing development or any testing.

73, Bob