Sound Stage and Imaging

Soundstage is all about room interaction (wall reflections). It is important to have even dispersion as you get off axis so the reflections don’t color the tonal balance of the speaker.

For $2000 used you can get a pair of Revel F208. They measure exceptionally well and throw a huge sound stage and can play real loud. The bass could use a sub for my tastes but a slightly high bass roll off is their only flaw in their price range. They put a lot of speakers costing a lot more to shame. There are a few pairs on audio mart in your price range. 

Tekton Design is within your budget and will provide the sound quality you are looking for. Today’s listings include a pair off Double Impacts for $1,900. There is a lot of positive reviews online for these speakers.

A nice pair of Vandersteen model 2 or 3 can be had used in that range. They are fiddely to set up meaning they really need space from the front wall, to be placed far apart with little to no toe in. They are capable of achieving a huge soundstage with wonderful imaging of done property. 

I agree that speakers are the biggest part of the solution but some attention needs to be paid to electronics as well. 

Tekton: before the current B&W Nautilus 804 I had the Mini Lore (bought after in house testing several others in the large room with sub). 

Vandersteen: friend has a set of 2c (3 way IIRC), terrible room/setup. But will pay more attention next time. First time casual listening, I liked how 'easy/natural' they sounded.