You do not need a DAW for amp sims, as a rule, but using a DAW can make things easier. Most amp simulators can be used as standalone programs, meaning you can run them without any additional software. All you need is your computer, your audio interface, and your guitar. That being said, using a Digital Audio Workstation (DAW) can make things a lot easier. A DAW is a software program that lets you record, edit, and mix audio. If you're using an amp sim to record guitar parts, a DAW can be a great tool for arranging your tracks, adding effects, and tweaking your tone. Many amp sims come in the form of VST plugins, which means they can be loaded into your DAW just like any other plugin. This allows you to use the amp sim as an effect on your guitar track and also gives you access to all of the other tools and effects that your DAW has to offer.