How many people and how big of a sweet spot? Reason I ask is because a lot of money can be spent satisfying a whole room, just to satisfy one person in the household who really cares. With that said, it is much easier, efficient and cost effective to concentrate the immersive experience to a single seat in the near field, while the ambient music in the rest of the room can still be quite satisfactory to those who aren't so critical. I have a hybrid desktop/stand mount system that is incredible, and sounds as big as any concert hall when I close my eyes.
So good in fact, that I have procrastinated upgrading to a whole room system for 8 years by now, and have since created another similar large near field system of budget, used, and homemade components in my garage that compels me to spend 3-4 nights/week with it, as well. My hybrid desktop system still uses a very dated (albeit powerful) AVR for power that was supposed to be temporary. With 120 Watts/channel, 12" professional grade (Same Fusion-12 Tempests mentioned by ski2xblack) speakers. In that near space though, for concert hall level performance, I can easily get by with the potent 8" speakers I own as well and have done so extensively.
A lot of people don't know you can do this because it isn't audiophile complicated enough, but it really delivers the bang for the buck if you're trying to get concert level performance on the cheap. Think of it as very large headphones minus the cranial null from having the headphones clamped to your head. Still, the rest of the room still sounds quite good, in spite of this rather selfish arrangement.
The pair of larger speakers and subs behind the smaller speakers is what i typically listen to in this seat, but the smaller ones pictured are quite potent as well. I spent $75 on the speakers used, $75 for the used AVR and improved the speaker cabinets myself once I discovered how good they sounded. The PC I have anyway, and makes for an excellent streamer, CD player, music storage, video games, movies, you name it.
The AVR and subwoofer amp is in front of the desk between it and the wall, even though in the photo it looks like it is under the desk itself.