Hi Denez.
Do you have power a brick or wall wart to drive that source d'energie?
Are you planning to interface with a computer or external gear?
Why did you pick a single hi-hat module rather than a generic drum module/rom player with more sounds/instruments?

Other than that, it looks very workable with those utilities sprinkled in. The Outs is optional IMHO, you can feed your monitors/headphones from the A-138. Get a vca instead. Oh and a attenuverter will be needed for adjusting the cv coming from your lfo and env.

cheers,
Ralf