I have a 24 V switching psu that for some reason when hooked up to an amp makes the sound like a distorted mess like a wireless connection dropping in and out at the same time. It reads that it outputting 24 V ; when i pull the plug out the music sounds normal for a couple of seconds before the power dissipates.

It did work properly for a while, and i have tested the amp with another psu and its fine so definitely the psu.

Any ideas would be appreciated...

Thanks
MRO Supply

Try examining the psu output using an oscilloscope to see how much ripple you get. Try it open circuit, and then with the load connected. See how much the ripple increases with the load. Measure the current under load.