Well- seems like you do have some demanding audio needs
especially when you have an already decent system.
My buddy has the edifier s-something and it does sound pretty good- and yes, the highs are good, and the bass is strong... Mids are ok... Overall loud and clear. I didn't notice any bass distortion, but it is a little strong for my taste- cuz it started to drown out the satellites.
The point is: IMO: strong base will drown out mids/highs/sound quality, unless one is a basshead.
Theory would tell me that you would be happiest with the a5- they have the biggest woofers and deepest (lowest) freq response. They go down to 50hz-which is pretty darn good for a 2.0 system. But take heed: your subwoofer probably goes all the way down to 35hz or so. So don't expect that they will have stronger bass than your edifiers. -but the will definitely have punchier bass than most 2.1 systems in the $300 price range.
As far as your room size being medium-small ... any of these speakers will be sufficient to fill the room with sound.
I believe that they'd be CLOSE FIELD [in front of computer at desk] - so IMO stong-low bass really isn't as important as the other SQ aspects. I've learned and become acustomed to the importance of SQ -over boomboom bass [I use to love strong overpowering bass LOL].
Anyways, I'm perfectly happy with the AudioEngine A2's for closefield listening.
For Movies and times that I want room filling sound, I have a Reciever and Klipsch Reference speakers for that.
Hope this helps
and not further confuse things.