I put a rack together that is roughly similar to the audio-path functionality of the Zoxnoxious synth. What is the Zoxnoxious synth? It's a set of voice cards that are controlled from VCV Rack. The voice cards have analog elements such as oscillators, filters, VCAs, etc. Each voice card has a correspoding VCV Rack module.
Obviously missing from this rack are any control elements: clocks, sequencers, LFOs, envelopes, etc are all missing. Those are all done in VCV Rack. Using VCV Rack allows for a ton cpu control over the voice card. In addition to VCV Rack generated controls, the Zoxnoxious voice cards can route signals between each other for modulation, filtering, etc. No audio goes through VCV Rack, only control elements. All audio is in the hardware synth.
Here's a rundown of the four cards I've developed so far and a rough Eurorack equivalent. Going left to right:
Z3340: Similar to most other 3340-based VCOs. I usually have two of these installed, hence two Kassutronics 3340s in this rack. The Zoxnoxious Z3340 has many more features such as four different sync modes that can be combined, and VCAs to mix the saw/pulse/tri outputs.
Pole Dancer filter: a bit similar to the A-107 morphing filter. The Pole Dancer is a multimode filter with direct access to a mixer for pole mixing. A separate module called the Personality provides the mixer (after all, a Pole Dancer needs a Personality!). Not only can one create many variations of low/high/band/notch filters but also morph/crossfade/switch/sequence between them.
Z3372: A filter + white noise generator in a single module; I dropped the AM8328 and Nse Noise Generator to represent it. The Z3372 is based around a clone of the CEM3372. It'll also do output panning which can be modulated by other voice cards.
Z5524: a 2-VCO + VCF module that is roughly like a combo of the Timo 3394 and WMD Legion. The Z5524 uses a modern TZFM VCO for one oscillator and the synth-on-a-chip CEM3394 clone for the VCO/VCF. There are some internal routings that give the hybrid character. The 3394 provides 6 different waveforms for TZFM modulation. The TZFM VCO also does hard sub-sync, where hard sync is one octave below the fundamental. Soft sync is also present, and both sync modes can be used at the same time for a more mellow hard sync.
With that lineup and all the control elements in VCV Rack this gives a pretty big analog palette to play with. Here's a demo video from a few years back: