This approach avoids using any computer or iPad, for people wanting to keep everything on the rack and make the best out of ES-9 internal mixer.
I always thought MIDI CC was meant to control levels on ES-9 standalone mode using an external MIDI controller. So I tried a different route: set up cv control on ES-9 using a CV to MIDI module (CV Thing) and a breakout (MIDIXO), and it works VERY well.
The first I tested is controlling the ¼” Main output level with a knob fixed 0-5V from Quadratt, this way I get a level control before the speakers like most interfaces do. Nice.
Then I tried Mod Medusa as envelope. The response is so good that ES-9 can take very short and fast envelopes to use internally. I think this hasn't been discussed, but it totally opens up ES-9 to CV control in very little footprint (4-6hp, all racked). All levels can be CVed, in mono or stereo: inputs, main output, phones mix, sends, sidechain... depending on you skills with the configuration tool 
If anybody is interested or uses ES-9 on standalone mode often, I can totally recommend getting a CV to MIDI module. Even for hosted mode you can get a bunch of mono or stereo VCAs before the DAW.
CVM-8 (ES cv to midi/i2c module) would be the best pairing since it has direct connection on the back of the module. This way, CVM-8 becomes an expander to ES-9, adding a highly configurable 8in 16out VCA matrix with offset and attenuation (range) per output.
It seems the internal ES-9 filters can't be controlled with MIDI, or at least I wasn't able to. If possible, all the inputs would gain mono or stereo voltage controlled filters.
Still amazed how well it works.
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