In the past i have worked with an old “wall wart” power supply which was not floating. This caused a lot of humming and grounding issues.
So i bought 2 power supply kits and a large toroid transformer at my local electronic shop.
I mounted all the stuff on a wooden board knowing that this is not the right way! It is just for development. Now i have ±15V with a current limit at 1A fully floating.
I am using PSK contacts for the whole synthesizer project.