-->Now, the JDS manual has some suggestions, recommending a linear(but not offering or suggesting one) rather than a simple switching PS, noting that switching supplies may cause some audible hum through the cans. <---
One of the quietest supplies I've designed from scratch was a switcher. It was quieter than even the fancy HP linear supply we had in the lab.
To roll a quiet hobbiest switcher from digikey parts you need a reasonable switcher with a filter on its output: So get
..a medical grade, switching, two prong wall wart rated for 1.5X to 3X the current you need. Both over sizing and under sizing the switcher is bad.
...a 1 ohm wire wound resistor. This resistor should be rated for the larger of 3X actual current used or 2X the rating of the wall wart. (1W for 0.58A load current or a 0.7A wall wart, 5W for 1.29A load or a 1.58A wall wart.)
....three 35V ~330uF to 1000uF -->low ESR<--- 3000 to 4000 hour aluminum caps and
.....a clamp on Ferrite bead ( LFB material)
Take the cord of the wall wart and wrap it three times through the clamp on bead. Put the bead a couple inches from the body of the wall wart.
Run the wall wart hot to the 1 ohm resistor then to the caps. Put the 3 caps in a "line" like tanker cars on rail road tracks where the tracks are the leads on the caps. Power from the 1 ohm feeds into the left most cap. The first cap feeds cap #2. Cap #2 feeds cap #3. Cap #3 feeds your device. The leads on the caps can be 1/2 to 1 inch long. Make all solder joints 1/4 to 1/8 inch from the rubber seal on the cap.
The 1 ohm resistor keeps the wall wart from oscillating and provides ripple filtering.
The daisy chain line of caps uses the wiring inductance of the leads as a filter inductor.
The clamp on bead makes a common mode choke.
You may be very pleasantly surprised.
There is one step more you can do to make it better. Put heatshrink on six ~3/8 inch diameter LFB beads and put one bead on each lead going between the caps (one on + and one on ground) and one bead on each wire going to your amp. I doubt you'll need that, but it's cheap to try.
There has to be tape/ heatshrink on the outside of the 3/8 beads. The beads can go conductive after a while and short things out. I learned this the hard way. The beads supported 24V for weeks and burst into flames just as the boss walked by the lab. . .He laughed. . .I said something worse than "Ouch."
