Remote cable too much amps for golf 3 ignition switches

Hello I have for some time the problem that apparently my ignition switch does not withstand the required current of the remote connection. This should be sowiso quite sensitive with the Golf 3. I have already installed the 2nd starter switch and there are problems again. Radio and power amplifier spin etc. It always goes well for a while, then the problems come back. I guess the switch does not manage to control my Clarion Radio and my Signum Series power amplifier, so that the The power is too high for him. The switch costs only 12 euros and I did the installation in 10 minutes, therefore not quite so tragic, but so it can not go any further. I wanted to put a relay in between and am at the superior which one could take there. It should have as high a resistance as possible on the control line. Does jamend have a tip for me?