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.
Ableton Live with iPad as external instrument [on Windows]
I am thinking of investing in Ableton Live, but I would like to use my iPad synth apps as instruments. I have seen sketchy information that this is possible using the 'External Instrument' instrument, but it is rumoured to be inconsistent in operation. Also, most people running Ableton seem to have Mac hardware, which I don't 
I would like to know if anyone has experience of this, and if it works (well, or at all) on Windows. Also, having just more or less persuaded myself I could make do with the Intro version (£69), I think I have understood from the features lists that this doesn't have the External Instrument, so I would need the Standard version (£319)
I know I can try it out with the demo, which I will do in due course. But it's good to get the lie of the land before I start the clock.
Comments
you can also use the iPad with Ableton link and send the audio into Ableton and use a normal audio track. you can play with the free 90 days version of Ableton.
you can try ext. instruments with this free trial also.
https://www.ableton.com/en/trial/
Might be worth searching the forum as you might find some threads that have already covered this. I know at one point it was necessary to install additional software to make things work on Windows, so those threads might give you some suggestions for necessary software.
I just invest into a windows laptop and took the Live standard edition. It works very well. I have a IConnectAudio+ to interface everything. It worked with the intro version too. In fact, I am very surprised how good it is to have Ableton + IPad playing together. There is latency but nothing unsurmountable
@MarkH - the first thing to solve is how you're going to get audio from the iPad to Windows. the iConnectAudio 4C is a great way, but not cheap. Two audio interfaces, one outputting from the iPad connected to one inputting to the Windows PC is another, but introduces double the latency.
Maybe you already have a solution for this?
The cheapest way (free) is to use rptmidi then you can send midi from ipad/iphone to any synth or DAW running on your PC or midi from PC to ipad. https://www.tobias-erichsen.de/software/rtpmidi.html
Then record the audio output on whatever device your sending the midi to.
For recording audio you can use SonoBus which is also free but more prone to latency issues. If recording small chucks of audio its pretty good. You can find SonoBus in the app store and on the dev website you can download the PC version. https://www.sonobus.net/
I wasn’t really thinking about getting sound into Windows, more just about controlling the iPad instruments from Live. My audio currently routes from both iPad and PC through a mixer, so I can record the output from there.
a simple usb2midi interface connected to the ipad and then to your asio audio card would work
rtp-midi would work too as suggested above , but avoid wireless and buy a usb2ethernet for connectng to ipad and then to your pc (i bought a usb3 hub that had 3 ports plus one ethernet and worked)
you might try bluetooth midi if latemcy is acceptable using the midiberry app on windows store
Ahh. That's much easier then. I don't think you need any special version of Live for that. I do as much on the Lite version (on Mac, but it should make no difference).
Network Session / RTP Midi should work quite well over ethernet, requiring only a USB ethernet adapter as mentioned above. I haven't actually tried this with a PC though. Forget Wifi for this. You will never be happy with the results.
Another way is to use two USB to Midi DIN connectors, one on the PC and one on the iOS device. The two sets of DIN connectors can be joined OUT to IN and IN to OUT with adapters. Example products:
https://www.amazon.com/Cable-Upgrade-Professional-Converter-Keyboard-Recording/dp/B092QLPST8/
https://www.amazon.com/Cable-Matters-Coupler-Changer-Extender/dp/B08B1WR2CB/
I wish I could find the thread, but someone here reported success with this on a windows PC recently.
BTW, free Live Lite licenses are easy to come by if you want to try before buying. Koala Sampler is one such app that includes a free license. There are others.
That may have been my thread, I was asking
I did get the USB MIDI cables and they do work back to back, although I found they also interfered with the iPad audio out. Perhaps I need to get less-cheap ones!
Yes, I have just been watching the 18-part (or more) series on Koala by NervousCook$, when he mentions this. Although as I said, I think you need the more expensive version to use external instruments.
@MarkH said: I think you need the more expensive version to use external instruments.
The external instrument device makes using external instruments a tiny bit more comfortable by uniting the midi out and the audio in from the instrument on the same track (there may be additional advantages, that I don't know right now). But you can easily use one midi track for the midi output and one audio track for the audio input in any version of live.
OK, I will get around to giving it a try sooner or later!