How to isolate diferent devices using 12V DC.

I have a noise problem.

I have these devices to supply:

Magma Chassis: 12V
Laptop: 16V
Wireless headphones emisor: 12V
Portable preamp/AD: 6- 14V

I thought about using a 12V to 16V converter to the laptop, and so woul have all devices conected to 12V, and so could easily use the car battery, or AC using a 220V-12V psu.
The problem is that using the 12 to 16 V for the laptop, a high noise from the laptop enters in the other devices, especially the wireless emisor.
I would like to know if it could be isolated diferent the diferent devices to avoid noise between them.
I suppose I would must to filter, but would be enough?
The other solution, could be use the 220-16V for the laptop. But then to use with the car, would need an inverter. Would this option have more comsumption?
What do you recomend?

Check to see if there is a 12V car power supply available for your laptop. If not, try powering your existing converter from a small capacity 12V rechargable battery of the type used in large torches connected to the main car 12V supply through a high-current common-mode choke.

Try using a ground lift plug on the AC cord for your laptop. I had the same problem with switching noise until I isolated the AC ground.

[quote author="Boswell"]Check to see if there is a 12V car power supply available for your laptop. If not, try powering your existing converter from a small capacity 12V rechargable battery of the type used in large torches connected to the main car 12V supply through a high-current common-mode choke.[/quote]

That car power supply is just what I´m using. The noise occurs even working with battery and no AC plugged.
The car power supply is the one who transmit the noise from the computer, back to the 12V. When remove it, the noise, disappear.
The noise has relation with the computer cpu, because when open/close windows, it can be heared. So I assume the Car power supply is not very well designed, and so I guess if is posible to filter it.