Yes i know about the current draw, nice you measured it again.
In the past i build a lot of power supplies, most of them uses the LT3045, TPA’s and if i wanted more current the LT78xx or LM’s.
Nowadays i can recommended the Ian Canada ones, they uses 10x LT3045 parallel with Sense, so output wil always stays the same on different loads.
It’s not getting any better than this.
Well … i made ones an 3x LT3045 parallel with LiPo powered, completely free from mains but that’s another story.
Anyway i see you uses an thumbdrive …
I had (have) an issue with SSD on USB drive input problem which is an known issue now at Volumio support.
Wonder if you experience the same.