Trying to figure out all the Mesa cards and what to get

Im working on an old kondia fv-1 mill thats got an outdated cnc system, my plan is to hook the motors stright into a Linuxcnc set up and get rid of the old computer. Iv got 3 servo drivers to give signal too and have been trying to find a mesa card that can do that, im guess im under the wrong impression on whats its doing but iv seen a lot of 2-3 card set ups, im looking for a way to simply plug the servo drivers into a card that sends them a singal with the pc. Do i need that FPGA plus motion control card? Or can i just get by with one od the FPGA cards? Again im probobly confused on what thees cards are actually doing, iv mainly messed with old 3d printers, any explanations would be appreciated 

I shoukd have mentioned but the signal for the servos is +-15V, is there a good work aroud to up the V or something