Big thanks to @Technomadic for the loan of his Waldorf Iridium - the desktop incarnation of the larger Waldorf Quantum. We're pairing that with the Soma Cosmos Drifting Memory Station - (just reviewed) but it has a new Firmware - currently Beta, which adds a more traditional Looping option. This will be available as some point in the near future, but we thought we'd use it.
The Arturia Keystep 37 is plugged into the Iridium USB host port (no MIDI cables needed), the Iridium then goes directly into the Cosmos and out to the recording.
The Iridium is certainly a lovely piece of hardware with a ton of features and synthesis options - sadly we didn't have time to go into that, but the hardware is really lovely.