Madfloyd, if I understand your original post, this bass issue started when you added the capability to your system to reproduce frequencies from about 60Hz on down. I'm assuming that when you say you have "dialed in" the sub using your music server. (I hope those are lossless formats. ;-) ) I assume that means that you have the sub crossed in around 60-80Hz. That is well within what your vinyl rig is able to reproduce if set up properly. No news to you here since you've already started looking into this. What I can't say is how your VPI setup should sound from my own experience.
Damping fluid is usually applied to focus bass but using too much can also detract from the upper frequencies. This could result in the loss of air you mention. Too little could result in little or no weight to the music. I experience this with my Vector tonearm when adjusting damping.
As an outside observer I notice that you seem to be making large swings in your settings. IME that means it is very possible that you are skipping over the sweet spot. I would suggest trying to go back to a very neutral starting point. Level tonearm, around 1.9 VTF (assuming a broken in cartridge), little or no AS, damping fluid at the VPI recommended level. Listen and make very small adjustments from here, but remember that changing one parameter will affect another so go slow. Listen some more. I think you know the drill, but leave the fluid alone until you have determined that you really are getting closer to what you want to hear.
If you add a bit more fluid, I'm talking a few drops at a time, and bass impact improves then try backing off the VTF just a little, a few tenths of a gram, to see if the HF reproduction improves. If you remove a bit of fluid and HF improves, then try adding a tenth or two of VTF. This process of finding the best fluid level can be long, drawn out. Think days and weeks, not minutes and hours.
However, if you are not hearing any bass impact or air from this neutral position then I think you need to realize that there may be a limit to what your table and arm can do. It doesn't sound to me like the cartridge (assuming it is healthy) or any other components are in question. For any given combination of CDP and turntable it is entirely possible that one will outperform the other.
Also, I don't think you have mentioned where and on what your table is sitting.
