Motor boating sound when Squeezelite loads in picoplayer

I've been trying to beat back a noise issue while trying to build a portable player with 7" screen. My issue seemed to be caused by trying to use a dual output PSU. Today I tried separate PSU's. One for the RSP3, screen, hard drive, etc. and one for an 18w stereo amplifier. It works fine except for a very faint motor boating sound coming from the speakers. I noticed that the noise starts when Squeezelite loads. I'm using picoreplayer 3.20 with SL.

Oddly enough, to me, I don't hear any noise when using headphones hooked to the RCA outputs of the DAC+. Only when I run the output to a amplifier.

Any ideas or is it just a coincidence that the noise starts when Jivelite loads?

Thanks,

Howard