DO NOT ATTEMPT THIS UNLESS YOUR GUITAR AMP HAS A LINE-LEVEL OUTPUT. 
If it does, then you may connect the Line Out from the Amp to the sound 
card's Line In.  The same holds true for connecting the amp's Preamp Out, 
or Effects Loop Send - do not connect them unless they are line-level. 
NEVER connect the amp's Speaker Out to the sound card. 

AVOID CONNECTING 'PREAMP OUT' OR 'EFFECTS SEND' DIRECTLY TO SOUND CARD. 
A guitar amp has a lot of gain - it is designed to operate at high volumes 
with large amounts of distortion.  Therefore, the Preamp Out and Effects 
Send from a guitar amp have a LOT more gain than a typical "line-level" 
audio device.  A sound card is designed for more delicate signals. 
By connecting a guitar amp's outputs you run the risk of overloading 
and frying the sound card. 

NEVER CONNECT 'SPEAKER OUT' DIRECTLY TO SOUND CARD. 
Connecting the Speaker Out to the sound card's Line In will *FRY* the sound 
card!  This is because speakers require high voltage from a guitar amp - 
much too much for the delicate circuitry of a sound card. 

USE A MIXER. 
The best way to record the guitar on a PC is by using a mixer. 
Connect the Preamp Out or Effects Send from the guitar amp to a mixing 
board line-level input, and then take the line output from the mixer to 
the sound card's Line In.  Keep the volume controls low when you first
hook this up, then s l o w l y turn up the volume controls to get a good
level. 

TURN VOLUMES DOWN WHILE CONNECTING/DISCONNECTING CABLES. 
DO NOT connect or disconnect patch cables with the volume controls 
turned up - this can cause a damaging transient noise.  Just turn 
all the volumes down when you connect/disconnect any cables.
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