Re: Recording Question
With the correct plugs, you can do it physically. The problem is that there are two opportunities for signal level mismatches.
1) The Line Level output from your amplifier could be too hot for the input on your iRig.
2) The iRig output to the analogue (mic/line) socket of the computer may be too low. You may need to crank the input gain of the computer to get a worthwhile level.
The likelihood is that this system will introduce a lot of noise. Digital clipping anywhere in the signal chain would render your recordings unacceptable except as rough initial demos.