As I said, the AG03 (or AG06) has a built-in soundcard. It let’s you record as well as play back. Just plug your gear in as you would any mixer and presto, master output of your mixer available for recording. High (24-bit) quality as well. And I love having a volume knob to control my speakers/monitors and my headphones.
As for speakers. Tip one: 2017 = no need for amp/speaker combination anymore. The quality of powered speakers is such that you don’t need the extra hassle and cabling. Tip two: While it depends on what you will be listening to and why, this being a (digital) DJ forum, the best advice I can give you for practice and listening to dance music, with the added bonus of being able to take your speakers and play the odd house or BBQ party as well, is to get a pair of (used) small PA speakers – say 10″ – with stands. Get a good brand though. Or, especially if you want some more low end, you can look at the 2.1 systems many brands from HK Audio and LD Systems sell or 1.1 systems like RCF has. It depends on your quality desire and budget.