You use a VST host and do all the aplifiery bits (the tone shaping, distortion etc.) inside the computer in software. Software
Software wise you will need a VST host application of your choice (really, any will do), and effects, amplifier modelers and guitar cabinet modeler plugins. There
There is both great free and commercial software for this out there: A good starting point would be the excellent free "le poulin" plugins together with effects plugins you may find googling for free "VST effects". Search the interwebs for "cabinet impulse files", which are basically models of guitar cabinets and can be used by most cabinet modeling software (I recommend Le poulin's "Lecab"). In
In your VST host the signal chain then goes something like this: Input -> Effects -> Amp -> Effects -> Cab simulator -> Effects -> Output Of course you are free to put any or none effects wherever you want (Reverb generally goes after cab simulator, while distortion goes before amp etc.). If
If you want to foray into commercial software, there are three major contenders I know of: Amplitube (which also offers some of it's plugins free), Guitar Rig and Revalver. These come packaged with everything you need effects, amp and modeler wise. At least some of them can also be used in a standalone fashion (you just run the program, no VST plugin host needed). Hardware
Hardware wise you can run directly into your sound card, but you will have high latency issues and bad sound quality. You can get yourself a USB audio interface (essentially an external sound card) to alleviate this. They set you back about 130€ if you want a decent one (a cheap one might do the job, too).
- You can play with headphones or computer speakers and it will sound good at any volume.
- Unlimited flexibility Layout wise. You can use each plugin multiple times without having to buy it again. You can do stuff like reverb after cabinet simulator where you would have to mic a cabined and record it to do in hardware.
- Some of the free stuff is professional studio grade. Sound quality is way above practice amps.
- You can easily record yourself, practice over it, write yourself some drum loops to play along etc. The sky is the limit. Perfect for improvising.
- You are not locked into a limited number of sounds.
- Can't gig with it.
- Suffers from feature overload. You tend to tinker more and play less.
- Might be complicated if you are bad with computers.
- Lacks the mojo.
- Can't gig with it (well, you can, but I wouldn't. It's easier to just buy an amp).
- Easy to use.
- Can gig or just go to a friend and play together.
- Takes more space.
- Might not sound as good as software.
- If you want additional good effects, you have to buy them.
PS: If you use your PC's sound card to connect a guitar, get yourself the free ASIO4All driver. It's a low latency driver so the VST program can directly access your sound card. If you just use the regular driver, there is a noticablenoticeable delay between hitting a string and sound coming out of the speaker.