Why won't my iPad work with my devilsound DAC?

I have an iPad that's running regular iTunes. I tried to run in into my preamp through my devilsound 2.1 DAC. I get no sound at all. iPod doesn't work either. I used iTunes from my HP mini laptop and it works fine. What's gives? I bought the adapter so I can link the lightning usb cable from my iPad and iPod to the devilsound USB cable.
Any ideas? I'm new to the whole iTunes thing, so this may be simply operator error. I appreciate any ideas
I don't claim to be an expert on this but a couple things come to mind. The first is what format are you sending to your DAC? Maybe its just a compatibility issue. The second is are you sure that you can send a digital signal from the iPod/1Pad at all? (Through a cable and not wireless.) I was under the impression that it can't be done. I could be wrong on that one.
Just a possibility (worked for MAC Air. Might work for iPAD) ...click on the Apple
logo (upper left) then System Preferences. In "Sound", click Output...is your DAC
Thanks guys,
I don't even have the output option on any system menu on the iPad.
I guess I'll stick with the laptop.
Thanks for your help
Skipper, I believe your problem is that this DAC requires powering from the computer source, and the ipad and iphone won't power more than 100 mA. These idevices work just fine with selfpowered DACs using the lightning to USB adaptor. I found that I could run a computer powered USB DAC like the Meridian Explorer from my ipad by putting a powered USB hub between the two so that the idevice doesn't see a current pull from the DAC. This worked for me. Give it a try.

That said, you are inherently limited on how much music you can store on an idevice, which is not the case for a laptop. So, overall, you are better off using a laptop at home. You may want to bring your idevice and that portable dac with you when you travel though.