However, when I try to do the same thing using gain/distortion…
I assume that’s louder? In that case, you are probably overdriving the laptop’s preamp. You can try moving the laptop farther away from the amp, or maybe put a pillow over the laptop’s mic. (Both of those things are going to change the “character” of the sound.)
In general, the mic/preamp built into a laptop and the preamp in a consumer soundcard are worthless for “quality” recording. And the mic input on a computer is simply wrong for a good stage/studio mic which is low impedance balanced with an XLR connector.
…without a preamp…
You don’t need a preamp. You need an [u]Audio Interface[/u] (which has preamp with an XLR connector built-in). You can also get one with an instrument input, or a switchable mic/instrument input. The Shure SM57 is the most popular mic for recording guitar amps.
Or, you can get one of [u]these[/u] little “USB mic adapter” interfaces.
Another inexpensive option is to use a [u]Behringer UCA202[/u] to record directly. Then, you can use software to simulate the sound of a guitar amp & cabinet (and/or to simulate effects pedals).
Or, starting around $100 USD you can get a “studio” USB mic ([u]example[/u]). The cost-quality-convenience trade-offs are very good with a USB mic. But, you loose some flexability because you can only record from one of these at a time (no stereo or muli-track recording), and it won’t plug into a PA system.
Ive always done my recording acoustically by using a tape recorder, and I expected similar results; the recording wasnt amazing by any stretch, but it was audible at least, and I had no problem recording the distortion.
Ideally Id like to record it all directly, but Ive never made the attempt since the equipment is expensive. What I had in mind was a way to record the output as heard with earphones, and make the proper adaptations to record that sound onto the computer.
We still have not established for certain what the problem is because we have not heard the recording.
If you could post a couple of short audio samples as described in my first post then we would be in a much better position to be able to offer relevant advice.