Hello Stepfan Firstly, it is of course important that it is an extension cable, i.e. one with a plug and socket. Normally these cables are used for a connection from a source to the input of the amplifier. The cables are shielded, but usually only thin wires are used as no power needs to be transmitted. At the output of the amplifier, however, the power has to be transmitted to the speakers, so shielding is no longer important, but thick wires are an advantage. It will sound good, but not optimally. On the other hand, the power of the Z407 is not too high, so it could still work. Greetings Felix