Ok so my trailer is not whining I am!
I have noticed when I have my stereo is on and the furnance kicks on, i get increased converter whine.
I have come up with two possible solutions. Put a high current choke and large capacitor in the system just after the converter output.
or: Put a choke on the power line for the stereo.
I liek the idea of filter all of the DC out of the converter since it kep all the power clean. I also have easier access to the converter than the power for the stereo.
Has anyone else had this problem and solved it?