How can I get rid of the dirty audio signal I can hear when routing audio out from my iPad into my FocusRite Scarlett audio interface?
It's a 1/8 to 1/4 inch cable.
Are you tying the record the iPad into a computer? in that case skip the audio-interface and do it digitally using Lightning->USB cable...
Cool. Will do that but is there a way to clean up the signal via the audio interface?
The bigger question is why is your iPad hissing and crunching? That's not normal behavior unless you're running an app that's actively generating such sounds for effect. Have you ruled out the cable or adapters you're connecting it with being bad? Do you hear those noises when you conncect headphones? And when you plug other signals into your Scarlett in the same scenario is the signal clean?
You could try and use a noise gate on the Scarlett / input side to get rid of the noises at silence, but that's not going to do you any good when you're recording your material. I would try what @Samu suggested and make sure that signal is clean.
I had problems with this briefly last night after iOS prompted me to upgrade my powered USB3 adapter. Powering the iPad off and back on fixed it. Something to try if you haven't already.
also, AUM allows 'measurement mode' which greatly improves audio quality when used as a line source. still aint great.
Thanks for the feedback everyone. I ended up going with Lightning for audio out and Midimittr for routing and controlling my iPad as a vst in Ableton.