Question : Problem: No sound through line in

When I plug my mixer in the line in (or microphone) on my Vista PC the level meter displays that I have sound through, and I am also enable to record using "Sound Recorder". BUT I can't hear a thing until I playback the recorded sound. This also means that I have no sound when I try to use other recording applications, and ofcourse I have to hear what I play on my guitar while playing. Not afterwords.

So
I have checked and double checked that the line in is activated and that there is connection, but I can't hear the sound "live".

Any hints?

Answer : Problem: No sound through line in

I would suggest using http://www.asio4all.com/ ASIO4ALL, if you want to listen to what you play. I'm not sure how well traversed you are in this field, so forgive me if I over-explain;

When you record something, the sound has being processed by your soundcard before the output. What differs from playing a sound directly from the computer is that the sound from your line-in is an analog signal that first has to be encoded to a digital signal, before the output (which then decodes it again to an analog sound). What usually happens with normal onboard cards is that they have a very high latency - meaning that when you record a sound, you normally don't hear it until half-a-second or whatnot after you've actually made the sound.

Now for the problem in question; although I don't have an exact sollution for you as to why you don't hear the sound, having played around with a variety of sound cards on different machines/setups, I've found that when I'm having problems in one way or another, I always try it with ASIO4ALL. ASIO4ALL is a driver that sits as a layer on top of your normal sound card driver, which allows you to stream the input directly to your output (in lack of a better explanation), reducing latency significantly. A neat side-effect is that I've gotten inputs and outputs on some cards to work ONLY with ASIO4ALL, that wouldn't work anywhere else. I hope this will be the case for you here as well.

Once installed and set up correctly (I don't have it on this computer, so I can't remember the specific details, but its rather simple), go into your sound editing program and set ASIO4ALL as the sound card driver. If you still can't get it to work, then the problem is with the actual driver of the card and how it's configured. Since ASIO4ALL does not use the Windows Mixer, you can then at least rule out the problem being Windows.

Hope this helps :)