So I've got a few older pcbs for a low voltage tube headphone amp I built years ago - the Millett Hybrid - and was thinking I could put one together with my Pi3,IQAudio hat DAC, and WD passport HDD all in the same small enclosure and run it off the HPA's supply to use at work. The HPA needs 24VDC/750mA. I currently use the Pi/hat/hdd as a player using a 5V/2A pi wallwart.
Is there a good way to drop the 24VDC to 5VDC to run the Pi/DAC/HDD without massive heat dissipation? Also, would I need to look at filtering the power to the Pi to keep the noise down since both the amp and Pi will be tied to the same PS?
I used a LM317 regulator with a 24VDC wallwart for the amp I built in the past. It was well filtered and worked well (Tangent TREAD regulator). I thought maybe that for the amp and a buck converter for the pi. My concern is any noise from the buck.
The whole thing will be going in a 6” x 9” enclosure. The amp pcb is 4x6”. Here are some pics of my old amp (it’s just the top half enclosure) with the small regulator and the bare pcb in the enclosure for size reference.