Use the optical output to an outboard DAC. I'd rather Apple kept the cost down.
If one has the cash to drop outboard D/A converters against every AE in their house, then I agree that's the way to go. But for now I'm not looking for an audiophile quality D/A converter -- just one that's as good as, say, the $40 DVD player sitting in my rack system. I have to think that with Apple's scale, the D/A converter could be much improved with little impact to cost.