I had problems connecting stereo computer speakers to the Etherwave Pro’s Audio Out socket using a stereo jack.
If you do this, the Standby switch has no effect and the Audio Out is permanently on.
The reason for this is that the Audio Out uses a balanced 3-pole socket (the manual incorrectly says it’s unbalanced). A balanced output helps reduce hum and noise on the cable for studio and stage use, but you can also connect a 2-pole jack to this socket as an unbalanced output for standard effects boxes, mixers and amplifiers.
The solution is to use a mono to stereo adapter with stereo speakers such as those for MP3 players or computers.
I have spoken to the engineers at Moog Music. The Etherwave Pro manual is being changed to mention the balanced Audio Out socket and avoid these problems.