Let me start by saying that The River has the most counterintuitive MIDI architecture I know of, and the English manual doesn't exactly help.
I have found 4 ways to connect to a DAW.
OPTION A:
- connect with one USB cable, from the USB PANEL output on the back of The River.
- set up one Riverkey layer
L1 active: ON
source: River
destination: River
SYSTEM > Local Off: ON (to avoid double notes)
SYSTEM > Dump To USB: YES (to transmit knob movements)
PROs: setup with only 1 layer, transmits and receives knob movements
CONs: your DAW can only control The River, but not other synths connected to it (neither with MIDI nor CV)
OPTION B:
- connect with a pair of MIDI cables
- set up at least two Riverkey layers
L1 active: ON
source: River
destination: MIDI
L2 active: ON
source: MIDI
destination: River
L3 active: ON (for CV synths)
source: MIDI
destination: CV destinations
SYSTEM > Local Off: OFF
PROs: your DAW can control other synths connected to The River (MIDI THROUGH or CV)
CONs: slightly more complex setup, can't transmit knob movements
OPTION C:
- connect with one USB cable, from the USB KEY output on the back of The River.
- set up at least two Riverkey layers
L1 active: ON
source: River
destination: USB
L2 active: ON
source: USB
destination: River
L3 active: ON (for other MIDI synths)
source: USB
destination: MIDI
L4 active: ON (for CV synths)
source: USB
destination: CV destinations
SYSTEM > Local Off: OFF
PROs: your DAW can control other synths connected to The River (MIDI OUT or CV)
CONs: more complex setup, can't transmit knob movements
OPTION D:
- a mix of OPTION A+B or A+C
PROs: transmits and receives knob movements, and your DAW can control other synths (MIDI THROUGH or MIDI OUT or CV)
CONs: very complex setup, with two sets of cables
Other considerations:
The word "channel" in the manual sometimes stands for "River Channel" or "MIDI Channel". Likewise, "USB" may mean "USB KEY" or "USB PANEL".
"Dump to USB" should not be confused with the SYSEX Dump commands (Current, All Single, All Multi, The River). It means "transmit the panel controls (knob movements) via the USB PANEL out", it's not a data dump.