Assign the track you want to play back to an output on the desk. This can be a mono output (Mono Out 3) for a single track, or a stereo output (Stereo Out 1/2). The output you choose will map directly to the channel of the same number on the SSL AWS-924 Delta.
Make sure that the input for the selected track you have chosen is set to Line Input on the SSL Desk. When you press play, you should be able to see signal coming out of the channel meter.
Ensure that the channel is being sent to the mix bus, and that your monitor control is up at a suitable level. Then, turn up the master fader and you should hear sound.
