Can I use my computer as a amp?

Well depending the sound card and the speakers you may get enough to let you noodle around.

 

If you wanted to invest in modelling software, A very nice computer, an interface and so on. It could work but would cost you a lot of moolah.

 

Read through the instructions for the software and/or visit the software manufacturer's websites. It should tell you how to do the basics. Every recording software program that I have seen, tried or read about lets you just play without having to record. I use Line6 Riffworks and it lets me play and use effects, etc without having to record.

 

Thats if you want the quality of a nice amp. I already have a computer, and VERY fortunately I have a 2.1 surround sound, nothing fancy but it has a woofer) All I do is plug my bass in a "1/4 to 1/8" adapter and plug that into the "line in" on the the comp, should be a blue hole, versus "green" for the speaker out, and "pink" the mic in. The adapter costs like 3 bucks at radioshack. Then you go to your windows sound manager (click the speaker icon in the bottom right of your comp, make sure "line-in" is not muted, turn the slider all the way up, and adjust your speaker volume to taste!) Granted I dont have great sound here, and you may not need it, but it works, especially when I dont have an amp around. All it cost was a few bucks and a little thinking