I'm surprised this topic hasn't come up before. I've been using my iPad as a digital source in my main system for a couple of months now, and have been extremely pleased with the results.
I don't often have time to post comments here, but all this talk of camera kits and Wadia docks has spurred me to come forward and reveal the true secret to achieving iPad audio bliss: a bluetooth DAC.
No cables or connectors need apply. The iPad's built-in Bluetooth transceiver allows you to wirelessly output a digital signal to a DAC of whatever quality and/or price is most suitable to your needs.
The one I've been using is the Chordette Gem (from Chord Electronics in England), which is described as their "entry" model (US price: $799). Should this strike you as laughably cheap (and lacking all semblance of true audiophile cred), you can always spring for the QBD76 (a more reasonable $5995). I've not heard the QBD76, so can't speculate what kind of improvement the extra $5200 will buy, but I can say without hesitation that I've been extremely pleased with the Gem.
It should be mentioned that the Gem has a USB input, too, but so far I haven't had time to try it out, nor have I had a chance to compare the Gem critically with either my Wavelength Brick or my NAD M55 CD/SACD/DVD player. But after 200+ hours of break-in, it is clearly in the same league. Close listening would likely reveal differences among them, but these might easily be of the "different" but not necessarily "better" variety.
Highly recommended!
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