[kid vic]

For about $600 (or a little less), I would be able to get you a 2.1 setup, that you would like better the the current A5+
Pair of JBL LSR306 studio monitors ($300) and a Monoprice 10" sub-woofer ($180)
(plus tax & shipping)
So you would not have to spend $3000 for better sounding audio.
Or maybe spend $1000 for a pair of studio monitors (brand?) and add a sub-woofer ($200-$500)
(A sub-woofer designed to work with studio monitors)

Subs are best paired with the same brand speakers for nearfield and sealed is the best choice possible. I would suggest the OP get proper stands and do room treatment before even considering a sub, especially for small spaces seeing as it will definitely over power the room

 

[Sylanthra]

Do you have a pic of your current setup?

Sorry, no picture. But the room 14x16 feet. I sit in one corner with the wall on the right. It is about 3 feet from me. I can place the center speaker under the monitor and the front left and right on either side. There would be about 3 feet separation between them. The right rear speaker can be placed about 3 feet back against the wall. I can move it farther back because there is a book case in the way. If I place the left speaker 3 feet back on the left, it will be free standing in the middle of the room. I can move to the back wall, but then I need to room correct the sound. That would mean getting A/V receiver with that functionality, right? Or is there a more audio specific piece of hardware that does this job

 

[PurpleAngel]

Sorry, no picture. But the room 14x16 feet. I sit in one corner with the wall on the right. It is about 3 feet from me. I can place the center speaker under the monitor and the front left and right on either side. There would be about 3 feet separation between them. The right rear speaker can be placed about 3 feet back against the wall. I can move it farther back because there is a book case in the way. If I place the left speaker 3 feet back on the left, it will be free standing in the middle of the room. I can move to the back wall, but then I need to room correct the sound. That would mean getting A/V receiver with that functionality, right? Or is there a more audio specific piece of hardware that does this job

IMHO (In My Humble Opinion), a 5.1 speaker setup, is not something that would offer any real benefit, for your situation.
I tried using a 5.1 setup with my computer, ended up finding myself preferring to use headphones.
And you really have no need for all the features that a modern A/V receiver offer.