[Rastinny]

Thank you very much for your response! I agree the problem is very difficult to source and to solve. Last saturday I went out and bought a €65 extension lead supposed to 'ground' better and eliminate the noise but this has also failed to produce an improvement. The noise is relentless and I'm now out of idea's. The last thing I may try is to buy a new power adapter cable. This will put me back about €150 so I'd rather not but...
Any other suggestions are still welcome

Question? Is there a certain measurable range of noise which an audio jack from a laptop is expected to produce? How do you measure this, what is the unit of measurement and should this be specified in the computers technical specifications.
Could it be that the amp and the speakers I use are simply too sensitive and are made to process audio of a different input range?

How expensive is the transformer you suggest and how does it actually work.

The audio input at my mixer is analog (red and white).

Thank you for responding!

All Blessings!