Need help with noisy power supply/amplifier issue

Hi, Unfortunately my SB Radio died recently. It was my second most used SB and I really miss it for outdoor use. I have a few Raspberry pi's so I thought I'd try and make a replacement of sorts. I have a RSP3 with a HiFiBerry DAC+, a 7" touchscreen and a 2.5" hard drive. I would like to put the whole hing in a box with a couple of small speakers.

I purchased this power supply for the 12v and 5v combo output. It has enough current on the 5 volt out to run everything with the pi and not get the under voltage issue. And of course it has enough output on the 12 volt supply to run the 18Watt amplifier. Here are links to Amazon and both products...

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Now on to the issue. The 5 volt supply works great and if I run headphones off of the HiFiBerry DAC+, it's dead quiet. The 12 volt supply seems to work well on the amplifier and has no problematic noise unless I try to run both, the RSP3 and the amplifier at the same time. Then I get a high frequency squeal and some clicking noises. The noise does not increase in volume if I turn the volume up, but is loud enough at idle.

If I run either one off of a separate supply, there is no discernible noise.

Any help would be greatly appreciated.

Howard