Thanks all for the input.

The device I'm building is meant for selling to the general public.

I usually take care of all the usual pittfalls but in this case (with the adapter sold with the product) I thought a crowbar was the solution.
I have done some (production friendly) designing for 'the general public' and experienced no serious problems so far. It has been my job for a few years now.

Thinking about it : I'm going to take advantage of the power input range of my powersupply which is an SMPS. Min 9V , max 30V input.
And limit the voltage at about 20V. Many adapters are 9V, 12V so that's a nice limit I guess.

Powering the backlight by a CC is somewhat harder since I want to control the brightness of the backlight. But there will be drivers with a control input.
I'm going to look into that.

A few answers :

- The powerconnector I'm using is standard 2.1mm barrel connector because that is the connector the adapter has.
- My PCB is a doubled sided board. about 180x150mm with a solid groundplane. The device has a solid metal housing.
- Ofcourse I understand the musician desperation when the adapter fails. On the other hand : there's enough equipment running on mains which can also fail. And can't be fixed on stage. Ok : an adapter is more volnarable.

Brings me back to my original question. If I want to limit at 20V / 1.5A what polyswitch is best?