thanks for the replies. I will follow up with a couple of experienced modular builders and see if we can get some schematics made or something. I am still worried that the (5u) module will need -/+15, but in any case powering the board from a modular supply is def the more logical approach here.
One worry is that the Axo board only allows 2 CV outputs? or is this expandable?
*I do see that the axo can take 15v - "DC input (7-15V, 2.1mm center pin, center pin positive)" quoted from axo core specs page http://www.axoloti.com/product/axoloti-core/
Thus far, the design is powerblock that gives -/+15, Some sort of thing that changes the AC to DC for axo**, Some sort of magic to convert the 2 CV outs to 12/15 AC for the subsequent CV module.
**yeah seems like i didnt even know modules need DC power anyway..guess that makes it simpler. So I guess the difference is that modules usually need -/+ and axo just needs +