The Expert Sleepers manual says…
(Note - this feature was added in firmware v1.1.0.)
Without a USB connection, the ES-8 operates in ‘standalone’ mode. In this mode
- the incoming ADAT channels drive the ES-8’s analogue outputs
- the ES-8’s analogue inputs are available at the ADAT output
Since the ES-8 only has four analogue inputs, the last four ADAT output channels will be silent.
The ES-8 will sync to the incoming ADAT clock, if any. With no ADAT input, it will use its internal clock, in which case anything using the ES-8’s ADAT output will need to sync to the ADAT clock.
ADAT at Double Sample Rates
The ADAT protocol intrinsically only supports operation at 44.1 or 48kHz. Most audio interfaces that run at double sample rates (88.1/96kHz) use two ADAT ports and a variant of ADAT known as ‘SMUX’ to support this.
The ES-8 takes a different approach. At 88.1/96kHz, every other audio sample on the ADAT outputs is thrown away, reducing the signal to 44.1/48khz. Thus, the full channel count on an attached ES-3 (for example) is maintained even at 96kHz. Similarly, every audio sample arriving on the ADAT input is doubled up.
This basic sample rate conversation is likely to be fine if the signals are CVs. For audio, you might want to consider adding some filtering into the signal chain to avoid aliasing.
Note that the above only applies if the ES-8 is running at 88.1 or 96kHz. At 44.1/48kHz, everything is running at its natural rate, nothing is thrown away or fabricated, and there are no odd aliasing concerns.
Also, for the avoidance of doubt, if the ES-8 is running at 88.1/96kHz then its own analogue inputs and outputs are running at that rate.
Are you sure the ES-8 firmware is at least version 1.1.0 ?