The nice thing about the Audioengine A2+ is that they have their own built in DAC. My brother is a big Audioengine fan and has had a few different pairs for work, and everything they make sounds great, even the little A2's. When I upgrade my current PC speakers, it is likely going to be the A2+.
After having a 5.1 setup for gaming since the PS2 era, I finally made the switch to purely headphone gaming toward the end of last gen and I would never go back to a 5.1 or 7.1 setup. The benefits are further compounded by the fact that I play co-op games with friends online and we are always on voice chat, and headphones + mic is the way to go (god damn you voice chat + speakers people with horrible echo's and feedback. I don't want to hear my own voice through your mic!). I can't remember the last time I played a couch co-op game other than FIFA, where sound quality/surround isn't a make or break.. If you game with groups of people often, than I see the appeal of a surround system, in that case, go nuts. The new Rockband is the only thing on the horizon where I could see playing my PS4 through my living room speakers, instead of headphones.
A solid pair of stereo speakers for music and investing more in headphones for gaming is the way to go. Heck, my Playstation Gold headphones even give me better surround and immersion than my Logitech Z5500's ever did, and I would consider the gold headset the bottom end of "good" headphones. Even headphones in the $150+ range start to give you sound quality and levels of immersion that you would have to spend x10 as much on a surround setup and also have the convenience to be able to play games at higher volumes to get the benefits of the larger systems. A buddy of mine has a pretty excessive surround system and plays games at ridic volume to try to show off the system to me and I am like... ok that is probably great for movies, but a pair of open headphone Sennheisers that cost a quarter as much as your amp alone sound way better.... and you can play at any volume you want, any time of day. A perfect example was in Destiny, he never knew that chests made a subtle "glistening" noise that allowed you to easily know when you are near them by audio queue alone, something I immediately noticed due to headphones. I even know the exact direction the chest is in based on noise.
Tl;dr If you primarily game by yourself or online, the best "gaming speakers" are always going to be headphones. Buy speakers that suit your non-gaming needs, like music, podcasts, movies etc.
