For the sake of completeness, I will link to Martin Doudoroff's fantastic compilation of mixers. It is clear from that list that there is no solution for my simple task, likely because there is no tradition of stereo paths in Eurorack.
For any designers who might be reading, I will specify my ideal Stereo Crossfade Output Mixer. This is optimised for the least amount of contact during performance.
- Two stereo inputs (A and B), each with an attenuator (pot and CV control) and post-fader metering (LEDs).
- Two stereo outputs (main and cue):
- The first (main) output normalled to a pair of line-level outputs, with a level pot and metering.
- The second (cue) output normalled to a stereo headphone jack, with a level pot and metering.
- A cross-fader mixing the inputs to both the main output and the cue output (inverse of the main mix). Therefore, when the fader is all the way left, input A goes to main and input B to cue. When the fader is all the way right, input B goes to main and input A to cue.
- A switch for the headphone out, selecting main and cue.
My initial rack combined the WMD Axys stereo mixer with the Erica Synths Pico Out for headphones and Ladik A-541 for balanced line output. But this is cumbersome, requiring three modules in 13 HP. By contrast, the above spec can be achieved easily in 10 HP.