To use the SUBPAC with the Apollo twin, you will need an adapter, 1/4 inch male to 1/8th female, for example: Click here!
One thing to remember while using the SUBPAC is to never clip the unit. The LED will flash red if the SUBPAC is clipping. A good starting point to avoid this clipping is to make sure the intensity knob is at 50%.
To use the SUBPAC with studio monitors:
1 - Assuming your monitors are running out Monitor L/R on the Apollo Twin.
2 - Connect the adapter to the headphone out on your Apollo Twin.
3 - Connect the AUX cable that comes with the SUBPAC to the adapter.
4 - The other end of the AUX cable will go into the line in on the SUBPAC control box.
5 - On the Apollo twin, you can now toggle between your studio monitors level and SUBPAC level by clicking "monitor".
6 - This way you have independent volume control over the monitors and the SUBPAC. Be sure to play some reference tracks to get a good understanding of where you like your levels.
To use the SUBPAC with headphones:
1 - Connect the adapter to the monitor outs on the rear panel headphone out on your Apollo Twin.
2 - Connect the AUX cable that comes with the SUBPAC to the adapter.
3 - The other end of the AUX cable will go into the line in on the SUBPAC control box.
4 - Connect your headphones to the headphones out on the SUBPAC control box.
5 - On the Apollo twin, you can now toggle between your studio monitors level and SUBPAC level by clicking "monitor".
OR - if your headphones are 1/4 inch, you can duplicate the headphones output with this adapter: Click Here!
6 - Be sure to mute the monitor mix and only send volume to the headphones mix.