hi, i'm kinda confused on what a distortion pedal does... i know it's like an amp, it creates distortion but to what point? i know a marshall distortion pedal can't replace a marshall amp but how good are pedals as compared to real amps? thanks!
There are pedals out that distort your guitar so heavily you can't make out the notes. It's all opinion whether it will replace distortion from a cranked marshall. Some people have a certain pedal to get their specific tone. If you are in the shop for a distortion pedal, then go to a shop and plug in and try every distortion possible to see what you like.
so if i used one, would the gain on the amp be not necessary? i have a modeling amp, would i just use the preamp bypass (or tube preamp)?
Roight. Pedals aren't amps, cos amps amplify your sound, and pedals don't. Pedals can also give you flavors of tone that your amp can't. Say you have one distorted tone on your amp. You can use a pedal to create a different one. And then there's the obvious benefits of footswitchability built in.