I saw that Waves was pushing some ads online. If you're looking at Cobalt and from the responses you've received on this thread I would suggest, just from personal experience, getting the Renaissance Maxx Bundle from Waves if you haven't already. At the discount price it's at right now, I think it would be a wise choice...but, that's just my opinion. That's not free...let's move on to something that is...
This is pulrely opinion, but something that "appears" to mimic the Waves RenEQ sound quality, that I discovered, is a free plugin with 64bit internal processing and decent dithering with what seems to be Baxandall and Gerzon approximated cuves built into the algorithms; although, they don't admit it but I recognize those curves.
Plugin Link
Try that plugin on strings and place two light compressors back-to-back right after it. To each of the Comp's apply only a slight threshold just to get the top of the signal and apply about a 1.8:1 compression and see if you notice anything.
Realize, my goal is to address the thread topic in the most cost efficient way. Fortunately, free was the cheapest for now.
Good luck.