In case you missed them, read Part 1 here, Part 2 here, Part 3 here, and Part 4 here.
If you're going to use studio monitors you'll need to find the right audio interface for the job. Not only is it essential to send signal to your monitors it also allows you to record instruments and vocals. If you're someone who'd prefer working in headphones then this may not be for you, but if you're an aspiring vocalist or musician, then an interface might be a good call. Make sure before you purchase an interface that the drivers are compatible with your computer and you have the right adapter for any cables you might need.
Top Audio Interface Picks
A simple two-input/output design. The Scarlett 2i2 includes direct monitor, direct input control, and phantom power.
Similar to the 2i2 the Air is another well-designed simple two input/output interface with direct monitor control. It includes a midi direct input control, and phantom power as well.
A small yet powerful little interface. Taking up almost no room you have two mic/line inputs as well as full preamp gain control. The Audio Box also includes phantom power for condenser microphones.
The Big Knob is the best interface for the price. With 3 source inputs and 2 sets of monitor outputs, you can hook up multiple sets of studio monitors. With two XLR and ¼ inch input combinations, you have a recording studio at your disposal.