After builing a LM317 variable power supply a few years ago it was time to upgrade.
The easiest and probably safest way to upgrade is to start from scratch, and to stay away from the 230VAC.
Thats why a prebuild SMPS is a great way to start from.
I chose to use a fairly new ATX surplus PSU i had around but any 12V (and up) SMPS will do.
The handy part about a ATX supply is that it already has dedicated 3V3 and 5V lines. If you work with opamps you'll certainly love the -12V rail that is available too. Older supply's do have a -5V rail available as well.
Do note that an ATX supply does have the abbility to drive much higher currents then a 'normal' benchtop PSU, be carefull and keep track of the current. You could blow shit up with 500W.