wadia claims to be the only lossless digital out. A decent price as well.
But then you need a nice DAC else its useless.
Krell KID is like the costliest and gives an analogue out.
But then all these are very costly combinations.
Zeppelin is one of the costliest ipod dock speaker system - around 40k and I own one.
Its really a very good one and you can read my ad hoc review here: SoundS in Music: B&W Zeppelin Review
One of the recent and well received system another high end system is Review: Focal JMlab Focal XS 2.1-Channel Multimedia + iPod System | iLounge