Effects Pedal Power Supply Ground Loop Buzz: Isolated Input Jack On Amplifier, How To Fix

I reviewed this product on Amazon recently. came across this issue. It's a very inexpensive power supply but it works well except for this issue. Thankfully it can be fixed. Even a more expensive power supply from Godlyke has a similar issue but the hum is not as bad. the PSU has a primary side for the 120 volt AC side and the secondary is the 9 volt DC side. each of those are isolated from eachother because of the switch mode power supply transformer inside. the nature of such a PSU creates RFI if not properly filtered and grounded. this ground is expected to be connected through your pedals to your input jack of your amplifier which is typically grounded to the earth chassis. If you have isolated jacks (plastic ones with plastic nuts that mount to the amplifier) where they have no Earth chassis reference then you will get all of the noise that is not shunted to ground. Better designed and more expensive power supplies will add a few components like a resistor and a capacitor to negate a lot of this noise without having a direct connection to Earth to keep it isolated. This is just another perfect example that not all power supplies are created equal. Thankfully if you can identify what is happening the solution is usually straightforward for the fix :-). https://www.amazon.com/dp/B0951WHWPT/