Wow... this is going in like 65 directions at once...
The 1968 is a very nice mix compressor... I reckon it could be used for mastering as well... the EQ-2NV and the 1961 have a little less than nothing in common [other than the fact that they're both equalizers] so it's pretty tough to give a real "compare and contrast" [I think you can pretty much guess which one I prefer... but that's kinda natural when something has been designed for you... and no, I don't make a royalty on them so no, my preferance is purely from a sonic view point, not a commercial viewpoint].
As for "the best" EQ/compressor combination for warming up a digital signal"... ugh, the first part of that would be to have some serious [S-E-R-I-O-U-S!!!] D/A-A/D converters on either side of the "best EQ/compressor combo"... without great converters, you're already missing a big part of the improvement capabilities... something in the Lavry "blue" series or Crane Song "HEDD-192" kinda league would be my first suggestion... from there, it's going to be a matter of your sense of aesthetic.
You can certainly run the audio back through an API 3124... engage the pad and you should be fine... add an external pad to the output while cranking the input and you might find yourself really digging the hell out of it [or not, depends on your sense of aesthetic]
Best of luck with the search!!