Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.
Download on the App StoreAudiobus is the app that makes the rest of your setup better.
My first two synths - connecting them to interface
I just bought a Uno Synth and a Pocket operator factory. Now I´m having a bit of headache to connect them to my audio interface a Zoom u-44(thats connected to my iPad).
I've noticed right away that the Uno don´t send audio through the USB and only analog audio through output. But what cables do I need? Is it 1/8"mm stereo to 1/4" mono? Is it possible to hook it to the coaxial in on the Zoom? I´ve tried that but no sound in.
And the same for the Pocket operator do I need a 1/8" stereo or mono? to 1/4"mono or stereo?!
I´m confused and in need of help to be able to record play with my new little friends 
Comments
The co-ax cable on the zoom is a digital connection for spdif (Sony Phillips digital interchange format if I remember right)
The UNO has mono summed output so I think your 1/8 stereo to 1/4 mono cable should work.
Aha!! Of course a digital(spdif) input doesn´t work on a analog signal
Thannk you @BiancaNeve
I think with the pocket operator it outputs mono audio on one channel and sync on the other so if I’m right you would need one of these
https://www.amazon.com/Hosa-CMP-159-Stereo-Breakout-Cable/dp/B005HGM1D6 Or something similar.
Ok! But that one I can use even for the Uno? Just plug the one the signal go out to, right!?
I guess so - depends if you want to have both plugged in at once ie are you buying one or 2 cables