I run both my PC and Wii sound output through my stereo system, which only has one phono input. I was getting annoyed with having to constantly swap the cables over when changing from one to the other, so I had a look round for a suitable method of having both plugged in at the same time.

I found a 1x male phono to 2x female phono cable at Maplins, but they were £4.50 plus postage each, and of course I need two. A bit expensive I thought, then I found these on Amazon for 80-odd pence each. Great, and I ordered two.

The only problem is, as long as a PC input is connected to either phono channel the Wii output just doesn't get through on that channel. If I unplug the PC input, it doesn't matter which jack the Wii is connected to, the sound is fine. PC sound is fine irrespective of the Wii's status.

I suspect I'm going to have to go the whole hog and buy an audio switch box but if anyone knows otherwise any advice would be greatly appreciated

You should never ever connect two outputs to one input using a device that combines the two into one! You should always use a switch so that only one device is conencted to the amp at any one time.

This is all tied into things like input and output impedances. Basically if you connect two outputs together then both see a very much lower impedance than if only one were connected. This can cause one or other or both devices to drop their output signal so much that it effectively shuts down.

It shouldn't harm either device but is very much NOT the correct way to go about it. As you correctly point out in your final line a switch box is the only way to do it properly - bar getting a new amp with more inputs obviously

Something like this Phono switch box from Maplins would do.

Even worse than that it can in some circumstances cause the output to go U/S - it won't in most cases (especially with low power devices) but it can.

Switch box is the way to go.

I remember using a phone 2 into 1 adaptor many years ago, and the volume was very weak. A switchbox works perfect, but you need to get up and flick the switch over.



Dave

A lot of outputs have a low value resistor in series with the output which goes some way to preventing the amplifier stage driving the output destroying itself.

By far the worst thing you can do however is wire two loudspeaker outputs together! That is almost certainly guaranteed to introduce the uninitiated to the unique scent of frying transistors

I realised they won't blow up in most cases that's why I put my qualifier in. Many output circuits will have a more sophisticated current limiter than just a series resistor but some have very little (like speaker drivers as you pointed out) so the advice is don't take the chance.