Hi Mat !
I'd be tempted to suggest the Expert Sleepers ES-9, but it depends on what you mean by "mixing on hardware". If the output of that mix is a single stereo channel, it might not be for you, but I personally appreciate using it to multitrack the modular into Ableton. It has the added benefit of allowing the extensive use of things like compressors, limiters or even creative FX's on each track or buses, I can easily re-route that into the modular for more processing through physical modules, the sky is the limit... and I suppose latency is another one :-)
If you plan on sending midi information from Ableton to the modular through the ES-9, that's definitely doable with CV Tools although I believe you might need Max4Live to use those things...
D.
--- Voltage control all the things ---